MLK-22336-1 usb: ci_udc: Convert driver to DM_USB_GADGET

MLK-22336-1 usb: ci_udc: Convert driver to DM_USB_GADGET

Convert the ci_udc driver to driver model by using the uclass
UCLASS_USB_GADGET_GENERIC. The clk and power of USB controller and USB
PHY both are initialized by parsing the device tree nodes.

If CONFIG_DM_USB_GADGET is defined, we use the ci_udc driver in DM way,
if it does not defined, we can use ci_udc driver in its original Non-DM
way.

Move some USB PHY register definitions from ehci-mx6.c to
asm/mach-imx/regs-usbphy.h in order to share with DM usb gadget driver.

Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Reviewed-by: Ye Li <ye.li@nxp.com>