thermal: rcar_gen3_thermal: add suspend and resume support

To restore operation it's easiest to reinitialise all TSCs. In order to
do this the current trip window needs to be stored in the TSC structure
so that it can be restored upon resume.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>