intel-tco: switch ITCO_WDT to loadable module

The watchdog driver can't be y when MFD driver is a loadable module.
Switch the config from y to m to avoid cases when MFD driver is also
enabled as m.

See:
https://github.com/torvalds/linux/commit/b30c1a464c29baf646a5726d90ea3537e775ac85



Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>

features/intel-tco/intel-tco.cfg

 # SPDX-License-Identifier: MIT
-CONFIG_ITCO_WDT=y
+CONFIG_ITCO_WDT=m