drm/amd/display: add missing void parameter to dc_create_transfer_func

Add a missing void parameter to function dc_create_transfer_func, fixes
sparse warning:

warning: non-ANSI function declaration of function 'dc_create_transfer_func'

Signed-off-by: Colin Ian King <[e-mail]>
Reviewed-by: Harry Wentland <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/dc/core/dc_surface.c

···
 	kref_put(&tf->refcount, dc_transfer_func_free);
 }
 
-struct dc_transfer_func *dc_create_transfer_func()
+struct dc_transfer_func *dc_create_transfer_func(void)
 {
 	struct dc_transfer_func *tf = kvzalloc(sizeof(*tf), GFP_KERNEL);