usb: host: ehci-mxc: Remove the driver

The ehci-mxc driver was only used by i.MX non-DT platforms.

Since 5.10-rc1, i.MX has been converted to a DT-only platform and all
board files are gone.

Remove the ehci-mxc driver as there are no more users at all.

Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20201113171231.2205-1-festevam@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>