drm/radeon: fix 1 RB harvest config setup for TN/RL

commit dbfb00c3 upstream.

The logic was reversed from what the hw actually exposed.
Fixes graphics corruption in certain harvest configurations.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/gpu/drm/radeon/ni.c

@@ -1085,12 +1085,12 @@ static void cayman_gpu_init(struct radeon_device *rdev)
 
 	if ((rdev->config.cayman.max_backends_per_se == 1) &&
 	    (rdev->flags & RADEON_IS_IGP)) {
-		if ((disabled_rb_mask & 3) == 1) {
-			/* RB0 disabled, RB1 enabled */
-			tmp = 0x11111111;
-		} else {
+		if ((disabled_rb_mask & 3) == 2) {
 			/* RB1 disabled, RB0 enabled */
 			tmp = 0x00000000;
+		} else {
+			/* RB0 disabled, RB1 enabled */
+			tmp = 0x11111111;
 		}
 	} else {
 		tmp = gb_addr_config & NUM_PIPES_MASK;