rockchip: clk: rk3128: fix DCLK_VOP_DIV_CON_MASK

The DCLK_VOP_DIV_CON_MASK should cover only bits 8 through 15.
Fix this to remove an "integer-overflow on shifted constant" warning.

Fixes: 9246d9e ("rockchip: rk3128: add clock driver")
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
diff --git a/arch/arm/include/asm/arch-rockchip/cru_rk3128.h b/arch/arm/include/asm/arch-rockchip/cru_rk3128.h
index 3d8317e..90012c7 100644
--- a/arch/arm/include/asm/arch-rockchip/cru_rk3128.h
+++ b/arch/arm/include/asm/arch-rockchip/cru_rk3128.h
@@ -187,7 +187,7 @@
 	DCLK_VOP_SEL_MASK          = 1 << DCLK_VOP_SEL_SHIFT,
 	DCLK_VOP_PLL_SEL_CPLL           = 0,
 	DCLK_VOP_DIV_CON_SHIFT          = 8,
-	DCLK_VOP_DIV_CON_MASK           = 0xfff << DCLK_VOP_DIV_CON_SHIFT,
+	DCLK_VOP_DIV_CON_MASK           = 0xff << DCLK_VOP_DIV_CON_SHIFT,
 
 	/* CRU_CLKSEL31_CON */
 	VIO0_PLL_SHIFT		= 5,