drm/i915: make intel_sdvo_regs.h self-contained

Ensure intel_sdvo_regs.h is self-contained and remains that way.

v2:
- include <linux/compiler.h> for __packed (Chris)

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190613100818.24800-1-jani.nikula@intel.com

drivers/gpu/drm/i915/Makefile.header-test

@@ -56,6 +56,7 @@ header_test := \
 	intel_quirks.h \
 	intel_runtime_pm.h \
 	intel_sdvo.h \
+	intel_sdvo_regs.h \
 	intel_sideband.h \
 	intel_sprite.h \
 	intel_tv.h \

drivers/gpu/drm/i915/intel_sdvo_regs.h

@@ -24,6 +24,12 @@
  *	Eric Anholt <eric@anholt.net>
  */
 
+#ifndef __INTEL_SDVO_REGS_H__
+#define __INTEL_SDVO_REGS_H__
+
+#include <linux/compiler.h>
+#include <linux/types.h>
+
 /*
  * SDVO command definitions and structures.
  */
@@ -731,3 +737,5 @@ struct intel_sdvo_encode {
 	u8 dvi_rev;
 	u8 hdmi_rev;
 } __packed;
+
+#endif /* __INTEL_SDVO_REGS_H__ */