usb: gadget: mv_udc: drop ARCH dependency

This patch do the following things:
1. Change the Kconfig information.
2. Rename the driver name.
3. Don't do any type cast to io memory.
4. Add dummy stub for clk framework.

Signed-off-by: Neil Zhang <zhangwm@marvell.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>