drm/omap: add extern C guard for the UAPI header

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NEmil Velikov <emil.l.velikov@gmail.com>
Acked-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

include/uapi/drm/omap_drm.h

@@ -22,6 +22,10 @@
 
 #include "drm.h"
 
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 /* Please note that modifications to all structs defined here are
  * subject to backwards-compatibility constraints.
  */
@@ -114,4 +118,8 @@ struct drm_omap_gem_info {
 #define DRM_IOCTL_OMAP_GEM_CPU_FINI	DRM_IOW (DRM_COMMAND_BASE + DRM_OMAP_GEM_CPU_FINI, struct drm_omap_gem_cpu_fini)
 #define DRM_IOCTL_OMAP_GEM_INFO		DRM_IOWR(DRM_COMMAND_BASE + DRM_OMAP_GEM_INFO, struct drm_omap_gem_info)
 
+#if defined(__cplusplus)
+}
+#endif
+
 #endif /* __OMAP_DRM_H__ */