i2c: riic: Enable runtime PM autosuspend support

i2c: riic: Enable runtime PM autosuspend support

Enable runtime PM autosuspend support for the RIIC driver. With this, in
case there are consecutive xfer requests the device wouldn't be runtime
enabled/disabled after each consecutive xfer but after the
the delay configured by user. With this, we can avoid touching hardware
registers involved in runtime PM suspend/resume saving in this way some
cycles. The default chosen autosuspend delay is zero to keep the
previous driver behavior.

Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>