USB: dwc3-msm: Use no-op USB PHYs for host only mode

DWC3 core driver requires USB PHYs to be present during init.
For this purpose dwc3-msm glue driver registers these PHYs
before adding dwc3 core device. But, USB2/3 PHY may not be
registered by dwc3-msm if it is operating in HOST only mode
when USB2 is running in OTG already. For this purpose DWC3
core driver should use no-op USB PHYs in host_only_mode.

Change-Id: Ic08864d1e4486b8951bc626f1f3c438c4335978e
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>