drm/i915: add VBT address and size fields to ASLE mailbox struct

To be used on systems where the VBT does not fit into the normal VBT
mailbox.

v3: rebase

Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Deepak M <m.deepak@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1448923632-16760-3-git-send-email-m.deepak@intel.com
[Jani: updated commit message]
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_opregion.c

@@ -120,7 +120,9 @@ struct opregion_asle {
 	u64 fdss;
 	u32 fdsp;
 	u32 stat;
-	u8 rsvd[70];
+	u64 rvda;	/* Physical address of raw vbt data */
+	u32 rvds;	/* Size of raw vbt data */
+	u8 rsvd[58];
 } __packed;
 
 /* Driver readiness indicator */