irqchip: bcm7120-l2: Fix missing nibble in gc->unused mask

This mask should have been 0xffff_ffff, not 0x0fff_ffff.

The change should not have an effect on current users (STB) because bits
31:27 are unused.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lkml.kernel.org/r/1415342669-30640-10-git-send-email-cernekee@gmail.com


Signed-off-by: Jason Cooper <jason@lakedaemon.net>