TOMOYO: Loosen parameter check for mount operation.

If invalid combination of mount flags are given, it will be rejected later.
Thus, no need for TOMOYO to reject invalid combination of mount flags.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>