phy: rockchip-typec: support DP phy switch

There are 2 Type-c PHYs in RK3399, but only one DP controller. Hence
only one PHY can connect to DP controller at one time, the other should
be disconnected. The GRF_SOC_CON26 register has a switch bit to do it,
set this bit means enable PHY 1, clear this bit means enable PHY 0.

Signed-off-by: Chris Zhong <zyw@rock-chips.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>