drivers: misc: ti-st: 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.

We expect both `kim_data->dev_name` and `kim_gdata->dev_name` to be
NUL-terminated.

`kim_data->dev_name` seems to not require NUL-padding.

`kim_gdata` is already zero-allocated and as such does not require
NUL-padding:
| kim_gdata = kzalloc(sizeof(struct kim_data_s), GFP_KERNEL);

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:
strscpy(dest, src, sizeof(dest))

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20231003-strncpy-drivers-misc-ti-st-st_kim-c-v2-1-79630447b0a1@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>