blkcg: remove unused @pol and @plid parameters

@pol to blkg_to_pdata() and @plid to blkg_lookup_create() are no
longer necessary.  Drop them.

Signed-off-by: Tejun Heo <tj@kernel.org>

diff --cc block/blk-cgroup.c
Simple merge

diff --cc block/blk-cgroup.h
Simple merge

diff --cc block/blk-throttle.c
Simple merge

diff --cc block/cfq-iosched.c
Simple merge