meta-quanta: gbs: cleanup for flash offset override syntax

flash offset override also need new syntax change

Signed-off-by: George Hung <george.hung@quantatw.com>
Change-Id: I589a4df8bf0a2a142bfc39504b72fad0026f4498
diff --git a/meta-quanta/meta-gbs/conf/machine/gbs.conf b/meta-quanta/meta-gbs/conf/machine/gbs.conf
index f2ab09c..8fb72f2 100644
--- a/meta-quanta/meta-gbs/conf/machine/gbs.conf
+++ b/meta-quanta/meta-gbs/conf/machine/gbs.conf
@@ -14,9 +14,9 @@
 GBMC_NCSI_IF_NAME = "eth0"
 
 # Overwrite flash offsets
-FLASH_KERNEL_OFFSET_flash-65536 = "2048"
-FLASH_ROFS_OFFSET_flash-65536 = "7168"
-FLASH_RWFS_OFFSET_flash-65536 = "62400"
+FLASH_KERNEL_OFFSET:flash-65536 = "2048"
+FLASH_ROFS_OFFSET:flash-65536 = "7168"
+FLASH_RWFS_OFFSET:flash-65536 = "62400"
 FLASH_SIZE = "65536"
 
 PREFERRED_PROVIDER_virtual/obmc-host-ipmi-hw = "phosphor-ipmi-kcs"