Update rockchip platform to not rely on undefined overflow behaviour

This consists of ensuring that the left operand of each shift is
unsigned when the operation might overflow into the sign bit.

Change-Id: Ib7fc54e4141cc4f1952a18241bc18671b36e2168
Signed-off-by: Justin Chadwell <justin.chadwell@arm.com>
diff --git a/plat/rockchip/rk3368/drivers/ddr/ddr_rk3368.h b/plat/rockchip/rk3368/drivers/ddr/ddr_rk3368.h
index 15912b5..6663bcb 100644
--- a/plat/rockchip/rk3368/drivers/ddr/ddr_rk3368.h
+++ b/plat/rockchip/rk3368/drivers/ddr/ddr_rk3368.h
@@ -222,7 +222,7 @@
 #define DDRPHY0_SRSTN_REQ(n)   (((0x1 << 0) << 16) | (n << 0))
 
 /* CRU_DPLL_CON2 */
-#define DPLL_STATUS_LOCK		(1 << 31)
+#define DPLL_STATUS_LOCK		(1U << 31)
 
 /* CRU_DPLL_CON3 */
 #define DPLL_POWER_DOWN			((0x1 << (1 + 16)) | (0 << 1))
@@ -237,7 +237,7 @@
 #define DDR_PLL_SRC_MASK		0x13
 
 /* DDR_PCTL_TREFI */
-#define DDR_UPD_REF_ENABLE		(0X1 << 31)
+#define DDR_UPD_REF_ENABLE		(0X1u << 31)
 
 uint32_t ddr_get_resume_code_size(void);
 uint32_t ddr_get_resume_data_size(void);