[201811][Arista] Add emmc quirks for Upperlake (#9970)

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.

Description for the changelog
Add emmc quirks for Upperlake

files/Aboot/boot0.j2

@@ -210,6 +210,7 @@ platform_specific() {
         aboot_machine=arista_7050_qx32s
         flash_size=3700
         echo "modprobe.blacklist=radeon,sp5100_tco" >>/tmp/append
+        echo "sdhci.append_quirks2=0x40" >> /tmp/append
     fi
     if [ "$sid" = "Upperlake" ] || [ "$sid" = "UpperlakeES" ]; then
         aboot_machine=arista_7060_cx32s
@@ -246,6 +247,8 @@ platform_specific() {
     echo "varlog_size=$varlog_size" >>/tmp/append
     # disable deterministic interface naming
     echo "net.ifnames=0" >>/tmp/append
+    # increase kernel log circular buffer size
+    echo "log_buf_len=1M" >>/tmp/append
 }
 
 get_uuid_for() {