wl1251: Replace strncpy with strscpy in wl1251_acx_fw_version

wl1251: Replace strncpy with strscpy in wl1251_acx_fw_version

strncpy() is deprecated [1] for NUL-terminated destination buffers since
it does not guarantee NUL termination. Remove the manual NUL termination
and replace strncpy() with strscpy() to ensure NUL termination of the
destination buffer.

Using strscpy_pad() to retain the NUL-padding behavior of strncpy() is
not needed because ->fw_ver is only used as a C-string.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Link: https://patch.msgid.link/20260111134301.598839-1-thorsten.blum@linux.dev
Signed-off-by: Johannes Berg <johannes.berg@intel.com>