fix(rockchip): add parenthesis for BITS_SHIFT macro

Signed-off-by: XiaoDong Huang <derrick.huang@rock-chips.com>
Change-Id: Ideac271469f0753c5b7aaed7bb07a792b64ae01e
diff --git a/plat/rockchip/common/include/plat_private.h b/plat/rockchip/common/include/plat_private.h
index 465f372..44a0c46 100644
--- a/plat/rockchip/common/include/plat_private.h
+++ b/plat/rockchip/common/include/plat_private.h
@@ -49,7 +49,7 @@
 #endif
 
 #ifndef BITS_SHIFT
-#define BITS_SHIFT(bits, shift)	(bits << (shift))
+#define BITS_SHIFT(bits, shift)	((bits) << (shift))
 #endif
 
 #ifndef BITS_WITH_WMASK