drm/radeon/evergreen_cs: fix missing break in switch statement

Add missing break statement in order to prevent the code from falling
through to case CB_TARGET_MASK.

This bug was found thanks to the ongoing efforts to enable
-Wimplicit-fallthrough.

Fixes: dd220a00e8 ("drm/radeon/kms: add support for streamout v7")
Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/evergreen_cs.c

@@ -1299,6 +1299,7 @@ static int evergreen_cs_handle_reg(struct radeon_cs_parser *p, u32 reg, u32 idx)
 			return -EINVAL;
 		}
 		ib[idx] += (u32)((reloc->gpu_offset >> 8) & 0xffffffff);
+		break;
 	case CB_TARGET_MASK:
 		track->cb_target_mask = radeon_get_ib_value(p, idx);
 		track->cb_dirty = true;