scsi: qla4xxx: ql4_mbx.c: Cleaning up missing null-terminate in conjunction with strncpy

Replacing strncpy with strlcpy to avoid strings that lacks null terminate.
And in some cases modified to copy one character less than the overall
length, as the entire area is already zeroed.

Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Acked-By: Nilesh Javali <nilesh.javali@qlogic.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>