board/xilinx: remove hash for Linux 6.6.60

Now that all Xilinx boards have been bumped to Linux 6.6.70, the Linux 6.6.60
hash can be removed.

Signed-off-by: Neal Frager <neal.frager@amd.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

board/xilinx/patches/linux/linux.hash

@@ -1,3 +1,2 @@
 # Locally calculated
-sha256  f59c7d260794d73ee519ba2579ef41aa8ac4985ac5af9461f94fa314969acd2e  xlnx_rebase_v6.6_LTS_merge_6.6.60.tar.gz
 sha256  b726226e8784d92049190f19768d393eccf3ad111c7a2e685bb29cfa1bdf1f70  xlnx_rebase_v6.6_LTS_merge_6.6.70.tar.gz