Kconfig: USB: Migrate CONFIG_USB_EHCI_HCD users to Kconfig

Migrate the rest of the users of CONFIG_USB_EHCI_HCD over to Kconfig.
For a few SoCs, imply or default y this if USB is enabled.  In some
cases we had not already migrated to CONFIG_USB so do that as well.

Cc: Marek Vasut <marex@denx.de>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Marek Vasut <marex@denx.de>