usb: Fix Kconfig unmet dependencies for Microblaze EHCI

Disable USB_ARCH_HAS_EHCI in arch Kconfig and enable it in usb Kconfig

Warning log:
warning: (MICROBLAZE) selects USB_ARCH_HAS_EHCI which has unmet
direct dependencies (USB_SUPPORT)

Signed-off-by: Michal Simek <monstr@monstr.eu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>