ixgb: repeat 32 bit ioremap cleanup

this patch has been made to many other drivers in kernel to fix
the storage of 64 bit resources in 32 bit variables.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>