drm/i915: protect HSW power well check with IS_HASWELL in redisable_vga

This may need work if other platforms do the same thing, but in the
meantime we should avoid looking at HSW specific bits in this generic
function.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
[added IS_BROADWELL too as that needs the same handling (Imre)]
Signed-off-by: Imre Deak <imre.deak@intel.com>
[danvet: Add Imre's missing sob.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -11032,7 +11032,7 @@ void i915_redisable_vga(struct drm_device *dev)
 	 * level, just check if the power well is enabled instead of trying to
 	 * follow the "don't touch the power well if we don't need it" policy
 	 * the rest of the driver uses. */
-	if (HAS_POWER_WELL(dev) &&
+	if ((IS_HASWELL(dev) || IS_BROADWELL(dev)) &&
 	    (I915_READ(HSW_PWR_WELL_DRIVER) & HSW_PWR_WELL_STATE_ENABLED) == 0)
 		return;