USB: misc: Add USB3503 High-Speed Hub Controller

This patch adds new driver of SMSC USB3503 USB 2.0 hub controller with HSIC
upstream connectivity and three USB 2.0 downstream ports. The specification
can be found from 'http://www.smsc.com/index.php?tid=295&pid=325'.

The current version have been tested very basic features switching the modes,
HUB-MODE and STANDBY-MODE.

Signed-off-by: Dongjin Kim <tobetter@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>