[SCSI] ibmvscsi: Enable fast fail feature

[SCSI] ibmvscsi: Enable fast fail feature

A new mode of error reporting, fast fail, has been added to the VIOS
which allows failover to happen more quickly.

If this new fast fail mode is enabled on the VIOS and the vSCSI client
supports the mode, the VIOS will not return MEDIUM error on path failures,
but rather return VIOSRP_ADAPTER_FAIL in the crq response, which
ibmvscsi will translate to DID_ERROR.

This new mode can be enabled for single path configurations as well,
so it is the new default error reporting mode. A module parameter is
provided to disable this new behavior on the off chance it causes a
problem on some old VIOS version.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>