[ARM] 4382/1: iop13xx: fix msi support

updates iop13xx msi support for a msi api change in 2.6.22

rev7:
* update for Michael Ellerman's "MSI: arch must connect the irq and the
  msi_desc" patch

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>