drm/i915/dsi: remove unused _MIPIA_AUTOPWG register definition

There are other unused registers, but this is also unusable and
inadequate. Remove.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/57afda02856a68f78fe4d30384d4f7b352b9a812.1713520813.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Author: jnikula

drivers/gpu/drm/i915/display/vlv_dsi_regs.h

@@ -93,9 +93,6 @@
 #define  TEARING_EFFECT_DELAY_SHIFT			0
 #define  TEARING_EFFECT_DELAY_MASK			(0xffff << 0)
 
-/* XXX: all bits reserved */
-#define _MIPIA_AUTOPWG			(VLV_DISPLAY_BASE + 0x611a0)
-
 /* MIPI DSI Controller and D-PHY registers */
 
 #define _MIPIA_DEVICE_READY		(_MIPI_MMIO_BASE(dev_priv) + 0xb000)