scsi_transport_spi: use spi target settings instead of inquiry data for DV

Right at the moment, we carefully set up the spi_support_xx in the
device configuration routines, but then we never actually use the
results: we rely on the inquiry strings.  If we're going to allow
overrides to the inquiry data, we have to rely on our own internal
settings.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>