[ARM] 3913/1: n2100: fix IRQ routing for second ethernet port

The second ethernet port on the Thecus n2100 was incorrectly assigned
to XINT1 instead of the correct XINT3 (PCI INTB instead of INTD), which
caused that port to be non-functional.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>