cpumask: use modern cpumask style in drivers/scsi/fcoe/fcoe.c

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: "James E.J. Bottomley" <James.Bottomley@suse.de>
Cc: Robert Love <robert.w.love@intel.com>
Cc: Chris Leech <christopher.leech@intel.com>
Cc: linux-scsi@vger.kernel.org