serial: rockchip: make ROCKCHIP_SERIAL depend on ARCH_ROCKCHIP

It looks like this line was copy-pasted, but not modified.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: NSimon Glass <sjg@chromium.org>

drivers/serial/Kconfig

@@ -111,7 +111,7 @@ config DEBUG_UART_SHIFT
 
 config ROCKCHIP_SERIAL
 	bool "Rockchip on-chip UART support"
-	depends on ARCH_UNIPHIER && DM_SERIAL
+	depends on ARCH_ROCKCHIP && DM_SERIAL
 	help
 	  Select this to enable a debug UART for Rockchip devices. This uses
 	  the ns16550 driver. You will need to #define CONFIG_SYS_NS16550 in