drm/i915: Pass atomic states to fbc update functions.

This is required to let fbc updates run async. It has a lot of
checks whether certain locks are taken, which can be removed when
the relevant states are passed in as pointers.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1463490484-19540-17-git-send-email-maarten.lankhorst@linux.intel.com
Reviewed-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>