ARM: at91: at91sam9n12: correct pin number of gpio-key
Correct pin number of gpio-key for at91sam9n12ek board.
The pioB4 is connect to LED, the pioB3 use as gpio-key.
Signed-off-by: Bo Shen <voice.shen@atmel.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>