USB: ezusb: move ezusb.c from drivers/usb/serial to drivers/usb/misc

This patch
- moves drivers/usb/serial/ezusb.c to drivers/usb/misc/
- renamed CONFIG_USB_EZUSB to CONFIG_USB_EZUSB_FX2 to avoid build errors
- adapts Makefiles and Kconfigs switching from bool to tristate for CONFIG_USB_EZUSB_FX2

Signed-off-by: René Bürgel <rene.buergel@sohard.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>