IMA: measure.policy: limit dont_measure tmpfs policy to func=FILE_CHECK

add func=FILE_CHECK to dont_measure tmpfs

Similarly to tcb.policy limit dont_measure tmpfs policy to func=FILE_CHECK.
This allows to do extra measurements, e.g. kexec boot command line, see
kernel commit

7eef7c8bac9a ("ima: limit the builtin 'tcb' dont_measure tmpfs policy rule")

Also remove leading 0 from tmpfs magic (to match IMA docs and tcb.policy).

Link: https://lore.kernel.org/ltp/20250203210233.1407530-1-pvorel@suse.cz/
Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Petr Vorel <pvorel@suse.cz>

Author: pevik

testcases/kernel/security/integrity/ima/datafiles/ima_policy/measure.policy

@@ -8,7 +8,7 @@ dont_measure fsmagic=0x62656572
 # DEBUGFS_MAGIC
 dont_measure fsmagic=0x64626720
 # TMPFS_MAGIC
-dont_measure fsmagic=0x01021994
+dont_measure fsmagic=0x1021994 func=FILE_CHECK
 # SECURITYFS_MAGIC
 dont_measure fsmagic=0x73636673
 measure func=FILE_MMAP mask=MAY_EXEC