scsi: mptfusion: Avoid possible run-time warning with long manufacturer strings

The prior strscpy() replacement of strncpy() here expected the
manufacture_reply strings to be NUL-terminated, but it is possible
they are not, as the code pattern here shows, e.g., edev->vendor_id
being exactly 1 character larger than manufacture_reply->vendor_id,
and the replaced strncpy() was copying only up to the size of the
source character array. Replace this with memtostr(), which is the
unambiguous way to convert a maybe not-NUL-terminated character array
into a NUL-terminated string.

Reported-by: Charles Bertsch <cbertsch@cox.net>
Closes: https://lore.kernel.org/all/5445ba0f-3e27-4d43-a9ba-0cc22ada2fce@cox.net/
Fixes: 45e833f0

 ("scsi: message: fusion: Replace deprecated strncpy() with strscpy()")
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240410023155.2100422-2-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>