[ARM] 4966/1: magician: add MFP pin configuration

Although the GPIO alternate functions should be correctly set
by the bootloader, configure them here to be sure.
To save power, FFUART/BTUART/STUART are left unconfigured (output, low)
until they are needed by pxaficp or the magician GSM chipset driver.

Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>