staging: octeon-ethernet: Add missing #includes.

I looks like something used to implicitly include linux/interrupt.h,
and no longer does.  Fix the resulting build error by explicitly
including it.

Signed-off-by: David Daney <david.daney@cavium.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>