drm/radeon/kms: fix sideport detection on newer rs880 boards

The meaning of ucMemoryType changed on recent boards, however,
ulBootUpSidePortClock should be set properly across all boards.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon_atombios.c b/drivers/gpu/drm/radeon/radeon_atombios.c
index b015915..6114198 100644
--- a/drivers/gpu/drm/radeon/radeon_atombios.c
+++ b/drivers/gpu/drm/radeon/radeon_atombios.c
@@ -1181,7 +1181,7 @@
 				return true;
 			break;
 		case 2:
-			if (igp_info->info_2.ucMemoryType & 0x0f)
+			if (igp_info->info_2.ulBootUpSidePortClock)
 				return true;
 			break;
 		default: