USB: misc: Add usb2533 hub driver with flex mode support

usb2533 HUB supports flex mode which allows swapping of upstream
port with one of the downstream port using I2C commands.
Add driver for the hub and enable/disable flex mode based on the
USB state (host/device).

CRs-Fixed: 2041232
Change-Id: I221edf3661e02fb368f99bbf6e8b247385ecabe0
Signed-off-by: Arumuga Durai A <cadurai@codeaurora.org>