[SCSI] mptfusion: Added sanity to check B_T mapping for device before adding to OS

Added sanity check before treating any device is a valid device.
It is possible that firmware can have device page0 in its table, but that
devicemay not be available in topology. Device will be available in topology
only if there is Bus Target mapping is done in firmware. Driver will always
check B_T mapping of firmware before reporting device to upper layer.

Signed-off-by: Kashyap Desai <kashyap.desai@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>