[Arista] Add emmc quirks in boot0 to improve reliability (#10013)

Why I did it
Fix some unreliability seen on emmc device with some AMD CPUs

How I did it
Added a kernel parameter to add quirks to
It depends on a sonic-linux-kernel change to work properly but will be a no-op without it.
The quirk added is SDHCI_QUIRK2_BROKEN_HS200 used to downgrade the link speed for the eMMC.

Author: Staphylo

files/Aboot/boot0.j2

@@ -630,6 +630,7 @@ write_platform_specific_cmdline() {
     if in_array "$platform" "crow" "magpie"; then
         cmdline_add amd_iommu=off
         cmdline_add modprobe.blacklist=snd_hda_intel,hdaudio
+        cmdline_add sdhci.append_quirks2=0x40
         read_system_eeprom
     fi
     if in_array "$platform" "woodpecker"; then
@@ -662,7 +663,6 @@ write_platform_specific_cmdline() {
     fi
 
     cmdline_add "varlog_size=$varlog_size"
-
     cmdline_add "sonic.mode=$sonic_mode"
 }
 
@@ -680,6 +680,9 @@ write_image_specific_cmdline() {
     # disable unified cgroup hierarchy to workaround dockerd limitation
     cmdline_add systemd.unified_cgroup_hierarchy=0
 
+    # increase kernel log buffer size
+    cmdline_add log_buf_len=1M
+
     # verbosity
     cmdline_add quiet
     # Start showing systemd information from the first failing unit if any.