ram: rockchip: Fix dependency of RAM_ROCKCHIP_DEBUG

The RAM_ROCKCHIP_DEBUG can be used only if DEBUG_UART is
available.
The next commit introduces changes in definition of debug
uart functions, so that DEBUG_UART is required to be defined
in order to initialize uart and use print functions.

Signed-off-by: Lukasz Czechowski <lukasz.czechowski@thaumatec.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
diff --git a/drivers/ram/rockchip/Kconfig b/drivers/ram/rockchip/Kconfig
index 67c63ec..d707d09 100644
--- a/drivers/ram/rockchip/Kconfig
+++ b/drivers/ram/rockchip/Kconfig
@@ -15,6 +15,7 @@
 
 config RAM_ROCKCHIP_DEBUG
 	bool "Rockchip ram drivers debugging"
+	depends on DEBUG_UART
 	default y
 	help
 	  This enables debugging ram driver API's for the platforms