drm/i915: Pass around plane_state instead of fb+rotation

intel_compute_tile_offset() and intel_add_fb_offsets() get passed the fb
and the rotation. As both of those come from the plane state we can just
pass that in instead.

For extra consitency pass the plane state to intel_fb_xy_to_linear() as
well even though it only really needs the fb.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470821001-25272-5-git-send-email-ville.syrjala@linux.intel.com