arm64: defconfig: remove CONFIG_USB_EHCI_MSM

No Qualcomm SoC requires the "ehci-msm.c" code any more.  So remove
the code, and remove the config option from the arm64 defconfig.

Suggested-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Andy Gross <andy.gross@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>