usb: host: remove ehci-msm.c

No Qualcomm SoC requires the "ehci-msm.c" code any more.  So remove it.

Suggested-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Alex Elder <elder@linaro.org>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Andy Gross <andy.gross@linaro.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>