isci: kill smp_discover_response_protocols in favor of domain_device.dev_type

This is step 1 of removing the contortions to:
1/ unparse expander phy data into a smp discover frame
2/ open-code-parse the smp discover fram into a domain_device.dev_type equivalent

libsas has already spent cycles determining the dev_type, so now that
scic_sds_remote_device is unified with isci_remote_device we can
directly reference dev_type.

This might also change multi-level expander detection as we previously only
looked at dev_type == EDGE_DEV and we did not consider the FANOUT_DEV case.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>