usb: dwc3-msm: Stop peripheral mode upon MHL cable connetion

After detecting MHL cable peripheral mode is no longer
required. Hence set id to float and bsv to false in order
to turn off usb gadget.

CRs-Fixed: 719314
Change-Id: I167429d5e2c2d9f184ec5823414f8e66eff18cd5
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>