MX: serial_mxc: cleanup removing nasty #ifdef

The serial driver for iMX SOCs is continuosly changed if a
new SOC or not yet used port is used. CONFIG_SYS_<SOC>_<UART Port>
defines were used only to find the base address for the selected UART.
Instead of that, move the base address to the board configuration
file and drop all #ifdef from driver.

Signed-off-by: Stefano Babic <sbabic@denx.de>
CC: Marek Vasut <marek.vasut@gmail.com>
CC: Wolfgang Denk <wd@denx.de>
CC: Fabio Estevam <fabio.estevam@freescale.com>
CC: Helmut Raiger <helmut.raiger@hale.at>
CC: John Rigby <jcrigby@gmail.com>
CC: Matthias Weisser <weisserm@arcor.de>
CC: Jason Liu <jason.hui@linaro.org>
Acked-by: Jason Liu <jason.hui@linaro.org>
diff --git a/include/configs/tx25.h b/include/configs/tx25.h
index f77c546..87bd8a6 100644
--- a/include/configs/tx25.h
+++ b/include/configs/tx25.h
@@ -90,7 +90,7 @@
  * Serial Info
  */
 #define CONFIG_MXC_UART
-#define CONFIG_SYS_MX25_UART1
+#define CONFIG_MXC_UART_BASE	UART1_BASE
 #define CONFIG_CONS_INDEX	1	/* use UART0 for console */
 #define CONFIG_BAUDRATE		115200	/* Default baud rate */
 #define CONFIG_SYS_BAUDRATE_TABLE	{ 9600, 19200, 38400, 57600, 115200 }