Include definitions of used types by including drm/drm.h

Sparse output:
/usr/include/drm/tegra_drm.h:21:
	found __[us]{8,16,32,64} type without
	#include <linux/types.h>
Signed-off-by: Emil Goode <emilgoode@gmail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>