drm/nouveau/nvif: fix dac load detect method definition

A thinko made me turn this into a u16 when cleaning up.

Spotted by coverity.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nvif/class.h

@@ -428,8 +428,8 @@ struct nv50_disp_dac_pwr_v0 {
 struct nv50_disp_dac_load_v0 {
 	__u8  version;
 	__u8  load;
-	__u16 data;
-	__u8  pad04[4];
+	__u8  pad02[2];
+	__u32 data;
 };
 
 struct nv50_disp_sor_pwr_v0 {