[ARM] 4611/2: AT91: Fix GPIO buttons pins on SAM9261-EK.

The incorrect GPIO pins are being initialized for the buttons on the
Atmel AT91SAM9261-EK board.  This buggy configuration turns LCD screen
blue...

Signed-off-by: Nicolas Ferre <nicolas.ferre@rfo.atmel.com>
Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>