drm/i915: Remove intel_modeset_suspend_hw

drm/i915: Remove intel_modeset_suspend_hw

Another layer of indirection for just an lpt-only w/a is a bit
excessive. Reduce it.

This was added in

commit 7d708ee40a6b9ca1112a322e554c887df105b025
Author: Imre Deak <[email protected]>
Date:   Wed Apr 17 14:04:50 2013 +0300

    drm/i915: HSW: allow PCH clock gating for suspend

Cc: Imre Deak <[email protected]>
Cc: Paulo Zanoni <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>
Reviewed-by: Imre Deak <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>