TOMOYO: Merge tomoyo_path_group and tomoyo_number_group

"struct tomoyo_path_group" and "struct tomoyo_number_group" are identical.
Rename tomoyo_path_group/tomoyo_number_group to tomoyo_group and
tomoyo_path_group_member to tomoyo_path_group and
tomoyo_number_group_member to tomoyo_unmber_group.

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