drm/i915: Flatten and rename haswell_set_pipemisc()

Move the platform checks out from haswell_set_pipemisc() and
rename it to bdw_set_pipemisc() to make it clear when to call it.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190412183009.8237-1-ville.syrjala@linux.intel.com


Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>