usb: Don't make USB_ARCH_HAS_{XHCI,OHCI,EHCI} depend on USB_SUPPORT.

The fact that an architecture/board has XHCI, OHCI or EHCI does not
depend on the fact that the kernel is configured with USB_SUPPORT.

Make the Kconfig reflect this fact thus avoiding ugly messages like:

warning: (MIPS_ALCHEMY && CAVIUM_OCTEON_REFERENCE_BOARD && SOC_AR71XX && SOC_AR724X && SOC_AR913X && SOC_AR933X) selects USB_ARCH_HAS_EHCI which has unmet direct dependencies (USB_SUPPORT)

Signed-off-by: David Daney <david.daney@cavium.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>