mxc: add MX3 support for i.MX internal UART driver

This patch adds MX3 support for the i.MX internal uart driver.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 9bc4276..0843c54 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -753,7 +753,7 @@
 
 config SERIAL_IMX
 	bool "IMX serial port support"
-	depends on ARM && ARCH_IMX
+	depends on ARM && (ARCH_IMX || ARCH_MXC)
 	select SERIAL_CORE
 	help
 	  If you have a machine based on a Motorola IMX CPU you