[SCSI] qla4xxx: allow hba to be online when initiator ip address is uninitialized

This patch provides the following:

1. remove warning ignoring the return value of pci_set_mwi()
2. allows HBA to be online when the initiator ip address is uninitialized.

Signed-off-by: David Somayajulu <david.somayajulu@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>