IB/ipath: Remove tests of PCI_MSI in ipath_iba7220.c

The PCI MSI interface is stubbed out properly so that all the
functions just return failure if PCI_MSI=n, so there's no reason to
have "#ifdef CONFIG_PCI_MSI" blocks in ipath_iba7220.c.

Signed-off-by: Roland Dreier <rolandd@cisco.com>