usb: phy: remove phy-msm-usb.c

No Qualcomm SoC requires the "phy-msm-usb.c" USB phy driver support
any more, so remove the code.

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