drm/i915: fix spelling mistake "reserverd" -> "reserved"

Fix a spelling mistake in a comment.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181120151415.32419-1-alexandre.belloni@bootlin.com

drivers/gpu/drm/i915/i915_debugfs.c

@@ -4352,7 +4352,7 @@ static void gen10_sseu_device_status(struct drm_i915_private *dev_priv,
 	for (s = 0; s < info->sseu.max_slices; s++) {
 		/*
 		 * FIXME: Valid SS Mask respects the spec and read
-		 * only valid bits for those registers, excluding reserverd
+		 * only valid bits for those registers, excluding reserved
 		 * although this seems wrong because it would leave many
 		 * subslices without ACK.
 		 */