drm/i915/bxt: apply clock gating workaround to all revisions

No need to cater for old A revisions.
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1487172099-24873-2-git-send-email-jani.nikula@intel.com

drivers/gpu/drm/i915/intel_pm.c

@@ -99,7 +99,6 @@ static void bxt_init_clock_gating(struct drm_i915_private *dev_priv)
 	 * Wa: Backlight PWM may stop in the asserted state, causing backlight
 	 * to stay fully on.
 	 */
-	if (IS_BXT_REVID(dev_priv, BXT_REVID_B0, REVID_FOREVER))
 	I915_WRITE(GEN9_CLKGATE_DIS_0, I915_READ(GEN9_CLKGATE_DIS_0) |
 		   PWM1_GATING_DIS | PWM2_GATING_DIS);
 }