scsi: ch: Replace deprecated strncpy() with strscpy()

scsi: ch: Replace deprecated strncpy() with strscpy()

strncpy() is deprecated for use on NUL-terminated destination strings [1]
and as such we should prefer more robust and less ambiguous string
interfaces.

These labels get copied out to the user so lets make sure they are
NUL-terminated and NUL-padded.

vparams is already memset to 0 so we don't need to do any NUL-padding (like
what strncpy() is doing).

Considering the above, a suitable replacement is strscpy() [2] due to the
fact that it guarantees NUL-termination on the destination buffer without
unnecessarily NUL-padding.

Let's also opt to use the more idiomatic strscpy() usage of: (dest, src,
sizeof(dest)) as this more closely ties the destination buffer to the
length.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20231023-strncpy-drivers-scsi-ch-c-v1-1-dc67ba8075a3@google.com
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>