drm/i915/dp: remove PANEL_POWER_OFF macro and its use

It's superfluous.
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/7987938a7950853ac3ee43c82fb9cbb0cd59a2fa.1547726792.git.jani.nikula@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -4687,7 +4687,6 @@ enum {
 #define  EDP_FORCE_VDD			(1 << 3)
 #define  EDP_BLC_ENABLE			(1 << 2)
 #define  PANEL_POWER_RESET		(1 << 1)
-#define  PANEL_POWER_OFF		(0 << 0)
 #define  PANEL_POWER_ON			(1 << 0)
 
 #define _PP_ON_DELAYS			0x61208

drivers/gpu/drm/i915/intel_dp.c

@@ -1000,8 +1000,7 @@ static int edp_notify_handler(struct notifier_block *this, unsigned long code,
 
 			/* 0x1F write to PP_DIV_REG sets max cycle delay */
 			I915_WRITE(pp_div_reg, pp_div | 0x1F);
-			I915_WRITE(pp_ctrl_reg,
-				   PANEL_UNLOCK_REGS | PANEL_POWER_OFF);
+			I915_WRITE(pp_ctrl_reg, PANEL_UNLOCK_REGS);
 			msleep(intel_dp->panel_power_cycle_delay);
 		}
 	}