Kconfig: USB: Migrate existing USB_EHCI_xxx options

The following options are migrated over fully now:
- USB_EHCI_ATMEL
- USB_EHCI_MARVELL
- USB_EHCI_MX6
- USB_EHCI_MX7
- USB_EHCI_MSM
- USB_EHCI_ZYNQ
- USB_EHCI_GENERIC

This also requires fixing the depends on USB_EHCI_MARVELL as it's used
by Orion5X and Kirkwood as well.

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