[ARM] pxa/colibri: add UART MFP configuration for the PXA320 module

[ARM] pxa/colibri: add UART MFP configuration for the PXA320 module

This patch configures the MFP pads for UART1, UART2, UART3 for the
Toradex Colibri PXA320 module. Previously they were just not
configured resulting in just the first UART working because it was the
only one that was configured by the bootloader (Toradex EBOOT in our
case).

This patch is against vanilla 2.6.30 and has been tested with the
Toradex Orchid carrier board (all three UARTs were functional).

Signed-off-by: Alex Roman <alex.roman@gmail.com>
Acked-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>