usb: dwc3-msm: Fix host-only mode support

Remove creation of no-op USB PHYs since the core is already
required to have actual PHYs registered. This fixes host-only
mode so that it can properly communicate with the HS & SS PHYs.

This effectively reverts commit 64d654ab ("USB: dwc3-msm: Use
no-op USB PHYs for host only mode").

Also, allow the dwc3-msm glue layer to directly query the dwc3
device tree node for the 'host-only-mode' property instead of
just relying on OTG xceiv being NULL.

Change-Id: I5198a46b66f1585539865b06d39bbd0e8e5f9ab0
Signed-off-by: Jack Pham <jackp@codeaurora.org>