configs/qemu_aarch64_sbsa_defconfig: bump ATF to 2.12

Since edk2-202408, ATF >= 2.12 is required for qemu aarch64 sbsa target
to support CPU topology information provided by edk2 firmware [1].

If ATF <= 2.11 is used, the boot will hand with the following error:

      sbsa_sip_smc_handler: unhandled SMC (0xc20000ca) (function id: 202)

In order to update edk2 package to a newer version, update ATF version
used by qemu_aarch64_sbsa_defconfig to 2.12.

[1] https://github.com/ARM-software/arm-trusted-firmware/commit/c891b4d83578db25d24d2a8e3e7e419e65773ac8

Cc: Julien Olivain <ju.o@free.fr>
Signed-off-by: Romain Naour <romain.naour@smile.fr>
Signed-off-by: Julien Olivain <ju.o@free.fr>

configs/qemu_aarch64_sbsa_defconfig

@@ -18,7 +18,7 @@ BR2_TARGET_ROOTFS_EXT2_SIZE="128M"
 # BR2_TARGET_ROOTFS_TAR is not set
 BR2_TARGET_ARM_TRUSTED_FIRMWARE=y
 BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_VERSION=y
-BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_VERSION_VALUE="v2.11"
+BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_VERSION_VALUE="v2.12"
 BR2_TARGET_ARM_TRUSTED_FIRMWARE_PLATFORM="qemu_sbsa"
 BR2_TARGET_ARM_TRUSTED_FIRMWARE_FIP=y
 BR2_TARGET_EDK2=y