misc: Port USB251xB/xBi Hi-Speed Hub Controller Driver from Linux

This patch adds a driver for configuration of the Microchip USB251xB/xBi
USB 2.0 hub controller series with USB 2.0 upstream connectivity, SMBus
configuration interface and two to four USB 2.0 downstream ports.

This is ported from Linux as of Linux kernel commit
5c2b9c61ae5d8 ("usb: usb251xb: add boost-up property support")

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Simon Glass <sjg@chromium.org>