drm/i915: Apply broader WaRsDisableCoarsePowerGating for guc also

commit 344df980 ("drm/i915/skl: Disable coarse power gating up until F0")
failed to take into account that the same workaround is used in guc
when forcewake is sampled.

Wrap the condition check inside a macro and use it in both places
to fix the guc side scope.

Cc: Dave Gordon <david.s.gordon@intel.com>
Cc: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Reviewed-by: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450286318-6854-1-git-send-email-mika.kuoppala@intel.com