kselftest/arm64: Fix check_tags_inclusion test

The check_tags_inclusion test reports the error below because the test
plan is not declared correctly:

# Planned tests != run tests (0 != 4)

Fix the test adding the correct test plan declaration.

Fixes: f3b2a26ca78d ("kselftest/arm64: Verify mte tag inclusion via prctl")
Signed-off-by: Vincenzo Frascino <[e-mail]>
Cc: Shuah Khan <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: Will Deacon <[e-mail]>
Cc: Gabor Kertesz <[e-mail]>
Cc: Amit Daniel Kachhap <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Will Deacon <[e-mail]>

tools/testing/selftests/arm64/mte/check_tags_inclusion.c

···
 	/* Register SIGSEGV handler */
 	mte_register_signal(SIGSEGV, mte_default_handler);
 
+	/* Set test plan */
+	ksft_set_plan(4);
+
 	evaluate_test(check_single_included_tags(USE_MMAP, MTE_SYNC_ERR),
 		      "Check an included tag value with sync mode\n");
 	evaluate_test(check_multiple_included_tags(USE_MMAP, MTE_SYNC_ERR),