selftests: filesystems: return Kselftest Skip code for skipped tests

selftests: filesystems: return Kselftest Skip code for skipped tests

BugLink: http://bugs.launchpad.net/bugs/1815234
[ Upstream commit 7357dcf2ef2811156fdf223a9a27f73528934e1f ]

When devpts_pts test is skipped because of unmet dependencies and/or
unsupported configuration, it exits with error which is treated as
a fail by the Kselftest framework. This leads to false negative
result even when the test could not be run.

In another case, it returns pass for a skipped test reporting a false
postive.

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

Change it to use ksft_exit_skip() when test is skipped.

Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
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>