[SCSI] zfcp: Update status read mempool

[SCSI] zfcp: Update status read mempool

Commit 64deb6efdc5504ce97b5c1c6f281fffbc150bd93 changed the way status
read buffers are handled but forgot to adjust the mempool to the new
size. Add the call to resize the mempool after the exchange config
data. Also use the define instead of the hard coded number in the fsf
callback for consistency.

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>