ARM: dts: imx25-pdk: Add UART1 pins

UART1 is the console port on mx25pdk board.

Add the pin configuration for UART1 port and also pass 'fsl,uart-has-rtscts'
to indicate that the port has RTS and CTS pins.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>