usb: dwc3: Add snapshot of DWC3 MSM drivers

This change adds dwc3-msm.c and dbm.c which together form
the driver for the USB controller on QTI MSM devices. Also
included are the Makefile, Kconfig, and supporting devicetree
bindings documentation. This snapshot is taken as of msm-4.9
commit 87d93e0ab37a ("drm/msm: limit sde_dbg_dump output to
current entries"). The files have been slightly modified to
correct minor checkpatch style warnings.

Change-Id: Ib25c9469d5242431209dcb0964bdf1c6b900f02b
Signed-off-by: Jack Pham <jackp@codeaurora.org>