ram: rockchip: rename sdram_common.c/h to sdram.c

rename sdram_common.c in arch/arm/mach-rockchip to sdram.c;
so that we can use the file name sdram_common.c in dram driver for
better understand the code;
clean the related file who has use the header file at the same time.

Signed-off-by: YouMin Chen <cym@rock-chips.com>
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/drivers/ram/rockchip/sdram_rk3188.c b/drivers/ram/rockchip/sdram_rk3188.c
index 03e3433..d3e4316 100644
--- a/drivers/ram/rockchip/sdram_rk3188.c
+++ b/drivers/ram/rockchip/sdram_rk3188.c
@@ -20,8 +20,8 @@
 #include <asm/arch-rockchip/ddr_rk3188.h>
 #include <asm/arch-rockchip/grf_rk3188.h>
 #include <asm/arch-rockchip/pmu_rk3188.h>
+#include <asm/arch-rockchip/sdram.h>
 #include <asm/arch-rockchip/sdram_rk3288.h>
-#include <asm/arch-rockchip/sdram_common.h>
 #include <linux/err.h>
 
 struct chan_info {