scsi: zfcp: support retrieval of SFP Data via Exchange Port Data

A new FCP channel feature allows us to read the diagnostics from our local
SFP transceivers. To make use of that add a flag
(FSF_FEATURE_REQUEST_SFP_DATA) to the feature-set we request from the FCP
channel. Whether the channel actually implements this can be determined via
an other new flag (FSF_FEATURE_REPORT_SFP_DATA), that is set in the
adapter_features field of the adapter structure after Exchange Config Data
finished.

Also add the corresponding definitions in the QTCB Bottom for Exchange Port
Data. These new definitions are only valid, if FSF_FEATURE_REPORT_SFP_DATA
is set.

Link: https://lore.kernel.org/r/ee1eba4de71eb06b4d82207ad4f428429346156f.1572018132.git.bblock@linux.ibm.com


Reviewed-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>