usb: phy: msm: Rename phy-msm-usb.c to phy-msm-qcom.c

This change is required to add the snapshot of
phy-msm-usb driver from 3.18 kernel to 4.9 kernel.
So henceforth on the internal tree, phy-msm-qcom will
be the glue driver for Qualcomm dev boards.

Change-Id: I999fdae44b6caa669a09c2ceb1685b550b9df0a4
Signed-off-by: Ajay Agarwal <ajaya@codeaurora.org>