usb: phy-msm-qusb: Add support for floating data lines detection

QUSB2 PHY supports Idp_src which can be used to detect if datalines
(DP and DM) are floating or not. dwc3-msm driver can use this info
to figure out if SDP detection was correct or not.

CRs-fixed: 1014099
Change-Id: I5fd2fce536b4fe3b1f69f27378a6cf9ca9ddcc8b
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>