[devices]: Fix configurations for 7050QX-32S-S4Q31 (#2119)

- Correct lane map in broadcom configuration
- Add writes to txdisable bits for SFPs in hwsku-init
- Add correct hwsku-init implementation for 201803 branch

Author: zzhiyuan

device/arista/x86_64-arista_7050_qx32s/Arista-7050QX-32S-S4Q31/hwsku-init

@@ -1 +1,52 @@
-echo 1 > /sys/devices/pci0000:00/0000:00:02.2/0000:02:00.0/mux
+#!/usr/bin/python
+from __future__ import print_function
+
+import mmap
+import os
+import sys
+from struct import pack, unpack
+
+class MmapResource( object ):
+   """Resource implementation for a directly-mapped memory region."""
+   def __init__( self, path ):
+      try:
+         fd = os.open( path, os.O_RDWR )
+      except EnvironmentError:
+         print( "FAIL can not open scd memory-map resource file" )
+         print( "FAIL are you running on the proper platform?" )
+         sys.exit( 1 )
+      try:
+         size = os.fstat( fd ).st_size
+      except EnvironmentError:
+         print( "FAIL can not fstat scd memory-map resource file" )
+         print( "FAIL are you running on the proper platform?" )
+         sys.exit( 1 )
+      try:
+         self.mmap_ = mmap.mmap( fd, size, mmap.MAP_SHARED,
+                                 mmap.PROT_READ | mmap.PROT_WRITE )
+      except EnvironmentError:
+         print( "FAIL can not map scd memory-map file" )
+         print( "FAIL are you running on the proper platform?" )
+         sys.exit( 1 )
+      finally:
+         try:
+            # Note that closing the file descriptor has no effect on the memory map
+            os.close( fd )
+         except EnvironmentError:
+            print( "FAIL failed to close scd memory-map file" )
+            sys.exit( 1 )
+   def read32( self, addr ):
+      return unpack( '<L', self.mmap_[ addr : addr + 4 ] )[ 0 ]
+   def write32( self, addr, value ):
+      self.mmap_[ addr: addr + 4 ] = pack( '<L', value )
+
+m = MmapResource( '/sys/bus/pci/devices/0000:02:00.0/resource0' )
+for addr in range( 0x5210, 0x5250, 0x10 ):
+    v = m.read32( addr )
+    m.write32( addr, v & ~( 1 << 6 ) )
+    print( "orig=%04x new=%04x" % ( v, m.read32( addr ) ) )
+
+with open( "/sys/devices/pci0000:00/0000:00:02.2/0000:02:00.0/mux_sfp_qsfp/direction", "w" ) as fdir:
+    fdir.write( "out" )
+with open( "/sys/devices/pci0000:00/0000:00:02.2/0000:02:00.0/mux_sfp_qsfp/value", "w" ) as fval:
+    fval.write( "1" )

device/arista/x86_64-arista_7050_qx32s/Arista-7050QX-32S-S4Q31/td2-a7050-q31s4-31x40G-4x10G.config.bcm

@@ -248,7 +248,7 @@ stable_size=0x2000000
 tdma_timeout_usec.0=15000000
 tslam_timeout_usec.0=15000000
 xgxs_lcpll_xtal_refclk.0=1
-xgxs_rx_lane_map_1.0=0x0123
+xgxs_rx_lane_map_1.0=0x3210
 xgxs_rx_lane_map_5.0=0x0321
 xgxs_rx_lane_map_9.0=0x1302
 xgxs_rx_lane_map_13.0=0x0213
@@ -280,7 +280,7 @@ xgxs_rx_lane_map_101.0=0x0213
 xgxs_rx_lane_map_102.0=0x1302
 xgxs_rx_lane_map_103.0=0x0123
 xgxs_rx_lane_map_104.0=0x2031
-xgxs_tx_lane_map_1.0=0x3210
+xgxs_tx_lane_map_1.0=0x0123
 xgxs_tx_lane_map_5.0=0x0321
 xgxs_tx_lane_map_9.0=0x2031
 xgxs_tx_lane_map_13.0=0x0213