s390/Kconfig: Make modules sanity test a module-only option

The modules sanity test must be built as a module to actually exercise
module loading. Require KUNIT && m to prevent built-in builds and avoid
misuse, so it is either 'n' or 'm'.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

Author: Vasily Gorbik

arch/s390/Kconfig

@@ -1024,7 +1024,7 @@ config S390_KPROBES_SANITY_TEST
 
 config S390_MODULES_SANITY_TEST
 	def_tristate n
-	depends on KUNIT
+	depends on KUNIT && m
 	default KUNIT_ALL_TESTS
 	prompt "Enable s390 specific modules tests"
 	select S390_MODULES_SANITY_TEST_HELPERS