platform/x86: think-lmi: Use strreplace() to replace a character by nul

platform/x86: think-lmi: Use strreplace() to replace a character by nul

We can replace
	p = strchrnul(str, '$OLD');
	*p = '\0';
with
	strreplace(str, '$OLD', '\0');
that does the compatible modification without a need of the temporary variable.

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230918135116.1248560-2-andriy.shevchenko@linux.intel.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>