drm/i915: Kill unused savePCH_PORT_HOTPLUG

We don't save/restore PCH_PORT_HOTPLUG so no point in reseving
space for the value.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200908140210.31048-1-ville.syrjala@linux.intel.comReviewed-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/i915_drv.h

@@ -543,7 +543,6 @@ struct i915_suspend_saved_registers {
 	u32 saveSWF0[16];
 	u32 saveSWF1[16];
 	u32 saveSWF3[3];
-	u32 savePCH_PORT_HOTPLUG;
 	u16 saveGCDGMBUS;
 };