drm/i915: unify gen6/gen8 rps irq handler
drm/i915: unify gen6/gen8 rps irq handler

After the previous patch the GEN8 RPS handler became very similar to the
GEN6 version, so unify the two functions.

No functional change.

Signed-off-by: Imre Deak <fbd5edba1988036c8923f0cca0cce6ac4811db29@intel.com>
Reviewed-by: Paulo Zanoni <cc0e04a2103c45cd195651d976f79813d0f66bdf@intel.com>
[danvet: Move one misplaced hunk from a later patch to fix a bisect
issue as reported by Wu Fengguang's 0-day builder and fix suggested by
Imre.]
Signed-off-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs