scsi: blkcg: Fix application ID config options

Commit d2bcbeab ("scsi: blkcg: Add app identifier support for
blkcg") introduced an FC_APPID config option under SCSI. However, the
added config option is not used anywhere. Simply remove it.

The block layer BLK_CGROUP_FC_APPID config option is what actually
controls whether the application ID code should be built or not. Make
this option dependent on NVMe over FC since that is currently the only
transport which supports the capability.

Fixes: d2bcbeab

 ("scsi: blkcg: Add app identifier support for blkcg")
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>