drm/i915: Module parameters using '-1' as default must be signed type

Testing i915_panel_use_ssc for the default value was broken, so the
driver would never autodetect the correct value.

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by:   Michel Alexandre Salim <salimma@fedoraproject.org>
Tested-by:     Michel Alexandre Salim <salimma@fedoraproject.org>
Cc: stable@kernel.org
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index d2da91f..4a9c1b9 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1000,10 +1000,10 @@
 extern unsigned int i915_powersave __read_mostly;
 extern unsigned int i915_semaphores __read_mostly;
 extern unsigned int i915_lvds_downclock __read_mostly;
-extern unsigned int i915_panel_use_ssc __read_mostly;
+extern int i915_panel_use_ssc __read_mostly;
 extern int i915_vbt_sdvo_panel_type __read_mostly;
 extern unsigned int i915_enable_rc6 __read_mostly;
-extern unsigned int i915_enable_fbc __read_mostly;
+extern int i915_enable_fbc __read_mostly;
 extern bool i915_enable_hangcheck __read_mostly;
 
 extern int i915_suspend(struct drm_device *dev, pm_message_t state);