[SCSI] libfc: fix symbolic name registrations smashing skb data

The strncpy for RSPN_ID and RSNN_NN requests was padding
past the allocated frame size.

Get the string length before filling in the ct header.

Signed-off-by: Joe Eykholt <jeykholt@cisco.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>