drm/radeon: Add break to switch statement in radeonfb_create_pinned_object()

Clang + -Wimplicit-fallthrough warns:

drivers/gpu/drm/radeon/radeon_fb.c:170:2: warning: unannotated
fall-through between switch labels [-Wimplicit-fallthrough]
        default:
        ^
drivers/gpu/drm/radeon/radeon_fb.c:170:2: note: insert 'break;' to avoid
fall-through
        default:
        ^
        break;
1 warning generated.

Clang's version of this warning is a little bit more pedantic than
GCC's. Add the missing break to satisfy it to match what has been done
all over the kernel tree.
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_fb.c

@@ -168,6 +168,7 @@ static int radeonfb_create_pinned_object(struct radeon_fbdev *rfbdev,
 		break;
 	case 2:
 		tiling_flags |= RADEON_TILING_SWAP_16BIT;
+		break;
 	default:
 		break;
 	}