defconfig: apq8084: Remove EHCI controller driver support

In apq8084 all usb cores USB3.0 based. Hence there is
no need for loading EHCI controller driver.

Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
Change-Id: Ib331b0ae8e1629049a780e43d045b5d0f4633673