brcm47xx: BCMA - Update default IRQ assignment per upstream change

Update the default IRQ assignment for unrecognized devices per
the upstream change.

Signed-off-by: Nathan Hintz <nlhintz@hotmail.com>


git-svn-id: svn://svn.openwrt.org/openwrt@35121 3c298f89-4303-0410-b956-a3cf2f4a3e73