x86: minnowmax: Configure GPIO pins to turn on USB ports VBUS

GPIO bank E pin 8 & 9 are used to control the on-board two USB ports
VBUS on/off. Let's configure them in the misc_init_r().

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-by: Stefan Roese <sr@denx.de>