[ARM] 4010/1: AT91SAM9260-EK board: Prepare for MACB Ethernet support

Add PHY IRQ pin definition for AT91SAM9260-EK board.

Signed-off-by: Wojtek Kaniewski <wojtekka@toxygen.net>
Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>