Fixed bug in skx subconfig related to bdd46f9.

Details:
- Fixed code in the skx subconfiguration that became a bug after
  committing bdd46f9. Specifically, the bli_cntx_init_skx() function
  was overwriting default blocksizes for the scomplex and dcomplex
  microkernels despite the fact that only single and double real
  microkernels were being registered. This was not a problem prior to
  bdd46f9 since all microkernels used dynamically-queried (at runtime)
  register blocksizes for loop bounds. However, post-bdd46f9, this
  became a bug because the reference ukernels for scomplex and dcomplex
  were written with their register blocksizes hard-coded as constant
  loop bounds, which conflicted the the erroneous scomplex and dcomplex
  values that bli_cntx_init_skx() was setting in the context. The
  lesson here is that going forward, all subconfigurations must not set
  any blocksizes for datatypes corresponding to default/reference
  microkernels. (Note that a blocksize is left unchanged by the
  bli_cntx_set_blkszs() function if it was set to -1.)

Author: fgvanzee

config/skx/bli_cntx_init_skx.c

@@ -101,12 +101,12 @@ void bli_cntx_init_skx( cntx_t* cntx )
 
 	// Initialize level-3 blocksize objects with architecture-specific values.
 	//                                           s      d      c      z
-	bli_blksz_init_easy( &blkszs[ BLIS_MR ],    32,    16,     3,     3 );
-	bli_blksz_init_easy( &blkszs[ BLIS_NR ],    12,    14,     8,     4 );
-	bli_blksz_init_easy( &blkszs[ BLIS_MC ],   480,   240,   144,    72 );
-	bli_blksz_init     ( &blkszs[ BLIS_KC ],   384,   384,   256,   256,
-	                                           480,   480,   256,   256 );
-	bli_blksz_init_easy( &blkszs[ BLIS_NC ],  3072,  3752,  4080,  4080 );
+	bli_blksz_init_easy( &blkszs[ BLIS_MR ],    32,    16,    -1,    -1 );
+	bli_blksz_init_easy( &blkszs[ BLIS_NR ],    12,    14,    -1,    -1 );
+	bli_blksz_init_easy( &blkszs[ BLIS_MC ],   480,   240,    -1,    -1 );
+	bli_blksz_init     ( &blkszs[ BLIS_KC ],   384,   384,    -1,    -1,
+	                                           480,   480,    -1,    -1 );
+	bli_blksz_init_easy( &blkszs[ BLIS_NC ],  3072,  3752,    -1,    -1 );
 	bli_blksz_init_easy( &blkszs[ BLIS_AF ],     8,     8,    -1,    -1 );
 	bli_blksz_init_easy( &blkszs[ BLIS_DF ],     8,     8,    -1,    -1 );