yocto-bsp: drop genericarm64 SRCREV

The OEcore SRCREVs now contain the fixes this machine specific
SRCREV was added to incorporate.

Dropping it to ensure that all reference boards are at the same
source and configuration level.

(From meta-yocto rev: 11d690061d67ab0f84265d609e129d8717e88bcb)

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta-yocto-bsp/recipes-kernel/linux/linux-yocto_6.12.bbappend

@@ -7,5 +7,3 @@ KMACHINE:beaglebone-yocto ?= "beaglebone"
 KMACHINE:genericx86 ?= "common-pc"
 KMACHINE:genericx86-64 ?= "common-pc-64"
 
-# Incorporate fixes post 6.12.3
-SRCREV_meta:genericarm64 = "9ee4baec963b10d213c060622fce6d2b34166f40"