quota: Set nofs allocation context when acquiring dqio_sem

dqio_sem can be acquired during inode reclaim through dquot_drop() ->
dqput() -> dquot_release() -> write_file_info() context. In some cases
(most notably through dquot_get_next_id()) it can be acquired without
holding dquot->dq_lock (which already sets nofs allocation context). So
we need to set nofs allocation context when acquiring it as well.

Signed-off-by: Jan Kara <jack@suse.cz>