ceph: split up __finish_cap_flush

This function takes a mdsc argument or ci argument, but if both are
passed in, it ignores the ci arg. Fortunately, nothing does that, but
there's no good reason to have the same function handle both cases.

Also, get rid of some branches and just use |= to set the wake_* vals.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>