soc: rockchip: io-domain: Remove incorrect and incomplete comment header

Fixes the following W=1 kernel build warning(s):

 drivers/soc/rockchip/io-domain.c:57: warning: Cannot understand  * @supplies: voltage settings matching the register bits.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Cc: Heiko Stuebner <heiko@sntech.de>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Doug Anderson <dianders@chromium.org>
Cc: linux-rockchip@lists.infradead.org
Link: https://lore.kernel.org/r/20201103152838.1290217-6-lee.jones@linaro.org


Signed-off-by: Heiko Stuebner <heiko@sntech.de>