ram: rk3399: migrate to use common code

For there are some structures and functions are common for all rockchip SoCs,
migrate to use the common code so that we can clean up reduandent codes.

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/Kconfig b/drivers/ram/rockchip/Kconfig
index daa5613..b75d581 100644
--- a/drivers/ram/rockchip/Kconfig
+++ b/drivers/ram/rockchip/Kconfig
@@ -11,8 +11,6 @@
 	help
 	  This enable sdram common driver
 
-if RAM_ROCKCHIP
-
 config RAM_ROCKCHIP_DEBUG
 	bool "Rockchip ram drivers debugging"
 	default y
@@ -23,18 +21,10 @@
 	  This is an option for developers to understand the ram drivers
 	  initialization, configurations and etc.
 
-config RAM_RK3399
-	bool "Ram driver for Rockchip RK3399"
-	default ROCKCHIP_RK3399
-	help
-	  This enables ram drivers support for the platforms based on
-	  Rockchip RK3399 SoC.
-
 config RAM_RK3399_LPDDR4
 	bool "LPDDR4 support for Rockchip RK3399"
-	depends on RAM_RK3399
+	depends on RAM_ROCKCHIP && ROCKCHIP_RK3399
 	help
 	  This enables LPDDR4 sdram code support for the platforms based
 	  on Rockchip RK3399 SoC.
 
-endif # RAM_ROCKCHIP