selftests: intel_pstate: return Kselftest Skip code for skipped tests

selftests: intel_pstate: return Kselftest Skip code for skipped tests

BugLink: http://bugs.launchpad.net/bugs/1815234
[ Upstream commit 5c30a038fb8ec8cdff011e6b5d5d51eb415381d4 ]

When intel_pstate test is 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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>