serial_mxc: add support for MX53 processor

This patch add UART support for Freescale MX53 processor

Signed-off-by: Jason Liu <r64343@freescale.com>
diff --git a/drivers/serial/serial_mxc.c b/drivers/serial/serial_mxc.c
index f96b21f..805f4c5 100644
--- a/drivers/serial/serial_mxc.c
+++ b/drivers/serial/serial_mxc.c
@@ -56,6 +56,12 @@
 #define UART_PHYS UART2_BASE_ADDR
 #elif defined(CONFIG_SYS_MX51_UART3)
 #define UART_PHYS UART3_BASE_ADDR
+#elif defined(CONFIG_SYS_MX53_UART1)
+#define UART_PHYS UART1_BASE_ADDR
+#elif defined(CONFIG_SYS_MX53_UART2)
+#define UART_PHYS UART2_BASE_ADDR
+#elif defined(CONFIG_SYS_MX53_UART3)
+#define UART_PHYS UART3_BASE_ADDR
 #else
 #error "define CONFIG_SYS_MXxx_UARTx to use the MXC UART driver"
 #endif