[SCSI] zfcp: Move debug data from zfcp_data to own data structure

The struct zfcp_adapter includes everything related to the debug
traces. This introduces dependences between the definitions in
zfcp_def.h and zfcp_dbf.h. Move all debug related data structures to a
new data structure to break those dependencies and manage the debug
data in zfcp_dbf.[hc].

Reviewed-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>