rockchip: puma: drop special handling of usb host regulator

With the current usb stack in u-boot, all host ports on puma work
flawlessly without any additional special handling, so drop that
usb hub hacking from the puma board.

Tested with mass-storage and usb-ethernet on both usb3 and usb2 ports.

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>