usb: usb3503: Convert to use GPIO descriptors

usb: usb3503: Convert to use GPIO descriptors

This converts the USB3503 to pick GPIO descriptors from the
device tree instead of iteratively picking out GPIO number
references and then referencing these from the global GPIO
numberspace.

The USB3503 is only used from device tree among the in-tree
platforms. If board files would still desire to use it they can
provide machine descriptor tables.

Make sure to preserve semantics such as the reset delay
introduced by Stefan.

Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Stefan Agner <stefan@agner.ch>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
[mszyprow: invert the logic behind reset GPIO line]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20191211145226.25074-1-m.szyprowski@samsung.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>