usb: ehci: use bus->sysdev for DMA configuration

Set the dma for ehci from sysdev. The sysdev is pointing to device that
is known to the system firmware or hardware.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Sriram Dash <sriram.dash@nxp.com>
Signed-off-by: Peter Chen <peter.chen@nxp.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>