rockchip: rk3288: use grf structure to access soc_con2

Prefer to use structure to access register if we can.
Signed-off-by: NKever Yang <kever.yang@rock-chips.com>
Reviewed-by: NPhilipp Tomsich <philipp.tomsich@theobroma-systems.com>

arch/arm/mach-rockchip/rk3288/rk3288.c

@@ -4,15 +4,17 @@
  */
 #include <asm/io.h>
 #include <asm/arch-rockchip/hardware.h>
+#include <asm/arch-rockchip/grf_rk3288.h>
 
-#define GRF_SOC_CON2 0xff77024c
+#define GRF_BASE	0xff770000
 
 int arch_cpu_init(void)
 {
 	/* We do some SoC one time setting here. */
+	struct rk3288_grf * const grf = (void *)GRF_BASE;
 
 	/* Use rkpwm by default */
-	rk_setreg(GRF_SOC_CON2, 1 << 0);
+	rk_setreg(&grf->soc_con2, 1 << 0);
 
 	return 0;
 }