syscalls/fchmod06: Convert to tst_acquire_device()

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
syscalls/utimes01: Convert to tst_acquire_device()

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
syscalls/mount01: Convert to tst_acquire_device()

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
syscalls/mount02: Cleanup & convert to tst_acquire_device()

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
syscalls/mount04: Cleanup & convert to tst_acquire_device()

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>