selftests: pstore: return Kselftest Skip code for skipped tests

When pstore_post_reboot test gets skipped because of unmet dependencies
and/or unsupported configuration, it returns 0 which is treated as a pass
by the Kselftest framework. This leads to false positive result even when
the test could not be run.

Change it to return kselftest skip code when a test gets skipped to clearly
report that the test could not be run.

Kselftest framework SKIP code is 4 and the framework prints appropriate
messages to indicate that the test is skipped.
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>

tools/testing/selftests/pstore/pstore_post_reboot_tests

@@ -7,13 +7,16 @@
 #
 # Released under the terms of the GPL v2.
 
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
 . ./common_tests
 
 if [ -e $REBOOT_FLAG  ]; then
     rm $REBOOT_FLAG
 else
     prlog "pstore_crash_test has not been executed yet. we skip further tests."
-    exit 0
+    exit $ksft_skip
 fi
 
 prlog -n "Mounting pstore filesystem ... "