x86: minnowmax: Remove incorrect pad-offset of several pins

Remove 'pad-offset' of soc_gpio_s5_0, soc_gpio_s5_1, soc_gpio_s5_2,
pin_usb_host_en0 and pin_usb_host_en1. These offsets are actually
wrong. Correct value should be added by 0x2000, but since they
are supposed to be 'mode-gpio', 'pad-offset' is not needed at all.

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