avr32: Add pin configuration choice to LCDC peripheral

This patch lets the board code choose which pin out to use for the LCD
interface.

On AT32AP7000 the LCDC is wired to two sets of pins, which lets the user
choose between dual ethernet and 32-bit EBI. For the ATNGW100 board it
is vital to have the choice to select the alternative pinout since this
pinout is routed to the external headers.

Update ATSTK1002 and ATSTK1004 to use the new interface.

Signed-off-by: Hans-Christian Egtvedt <hcegtvedt@atmel.com>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>