[SCSI] hpsa: enable bus master bit after pci_enable_device

pci_disable_device() disables the bus master bit and pci_enable_device does
not re-enable it.  It needs to be enabled.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>