board/xilinx: add Linux 6.12.60 hash

Add the hash for the Xilinx Linux 6.12.60 release tag.

Signed-off-by: Neal Frager <neal.frager@amd.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

board/xilinx/patches/linux/linux.hash

@@ -1,2 +1,3 @@
 # Locally calculated
 sha256  38aec9ce252ed6a0b64d294d4d58bf51e25b249eefb31b800a5ce62cb084298a  xlnx_rebase_v6.12_LTS_2025.2.tar.gz
+sha256  444f573cd4438af1f5062fd69fcc82965a56068e6a25cd43c062a68398f90b03  xlnx_rebase_v6.12_LTS_merge_6.12.60.tar.gz