[SCSI] ibmvscsi: Remove backend abstraction

Now that the iSeries code is gone the backend abstraction
in this driver is no longer necessary, which allows us to
consolidate the driver in one file.

The side effect is that the module name is now ibmvscsi.ko
which matches the driver hotplug name and fixes auto-load
issues.

[jejb:fix up checkpatch.pl errors]
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Robert Jennings <rcj@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>