drm/i915: s/__raw_i915_read32/I915_READ_FW/ in the SKL+ scanline read w/a

drm/i915: s/__raw_i915_read32/I915_READ_FW/ in the SKL+ scanline read w/a

Replace __raw_i915_read32() with I915_READ_FW() in the workaround for
the SKL+ scanline counter hardware fail. The two are the same thing
but everyone else uses I915_READ_FW() so let's follow suit.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170309154434.29303-3-ville.syrjala@linux.intel.com
Reviewed-by: Mika Kahola <mika.kahola@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>