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

Cc: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Acked-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>

include/uapi/drm/etnaviv_drm.h

@@ -19,6 +19,10 @@
 
 #include "drm.h"
 
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 /* Please note that modifications to all structs defined here are
  * subject to backwards-compatibility constraints:
  *  1) Do not use pointers, use __u64 instead for 32 bit / 64 bit
@@ -222,4 +226,8 @@ struct drm_etnaviv_gem_wait {
 #define DRM_IOCTL_ETNAVIV_GEM_USERPTR  DRM_IOWR(DRM_COMMAND_BASE + DRM_ETNAVIV_GEM_USERPTR, struct drm_etnaviv_gem_userptr)
 #define DRM_IOCTL_ETNAVIV_GEM_WAIT     DRM_IOW(DRM_COMMAND_BASE + DRM_ETNAVIV_GEM_WAIT, struct drm_etnaviv_gem_wait)
 
+#if defined(__cplusplus)
+}
+#endif
+
 #endif /* __ETNAVIV_DRM_H__ */