[SCSI] zfcp: Update message with input from review

Update the kernel messages in zfcp with input from the message review
and remove some messages that have been identified as redundant.

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