USB: pxa168: Add onchip USB host controller support

- Add EHCI Host controller driver
- Add wrapper that creates resources for host controller driver

v2 - Call clk_put() after clk_disable() in probe function

Signed-off-by: Tanmay Upadhyay <tanmay.upadhyay@einfochips.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>