ima_violations.sh: Declare tcb builtin policy

IMA builtin policy contains required rules, allow using it.
This helps more reliable results on kernels without
CONFIG_IMA_READ_POLICY=y.

Link: https://lore.kernel.org/ltp/20250114112915.610297-7-pvorel@suse.cz/
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Petr Vorel <pvorel@suse.cz>

Author: pevik

testcases/kernel/security/integrity/ima/tests/ima_violations.sh

@@ -10,6 +10,7 @@ TST_SETUP="setup"
 TST_CLEANUP="cleanup"
 TST_CNT=3
 
+REQUIRED_BUILTIN_POLICY="tcb"
 REQUIRED_POLICY_CONTENT='violations.policy'
 
 setup()