[SCSI] fusion: unloading the driver results in panic - fix

The ioc->alt_ioc->alt_ioc pointer is not getting cleared
during driver unload time.   This dangling pointer
can result in panic in certain circumstances, such
as error recovery, or firmware download in flashless
environments. This only impacts dual functions controllers,
such as 1030. Please apply.

This patch also includes a small cosmetic name change
for mpt_spi_log_info.

Signed-off-by: Eric Moore <Eric.Moore@lsil.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>