net/mlx5: simplify mlx5_set_driver_version string assignments

In total, just assigning this version string takes:
(1) strncpy()'s
(5) strlen()'s
(3) strncat()'s
(1) snprintf()'s
(4) max_t()'s

Moreover, `strncpy` is deprecated [1] and `strncat` really shouldn't be
used either [2]. With this in mind, let's simply use a single
`snprintf`.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://elixir.bootlin.com/linux/v6.6-rc5/source/include/linux/fortify-string.h#L448 [2]
Link: https://github.com/KSPP/linux/issues/90


Cc: linux-hardening@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>