usb: dwc3-msm: dbm: Merge dbm '1.4' into dbm-1_5.c

Since there is practically no functionality difference between
DBM versions 1.4 and 1.5, the two drivers can be combined. Add
the register offset table for 1.4 which will be chosen based
on the device tree compatible string.

Change-Id: Ibcb070846f02174c0225835617742a786f4c55d1
Signed-off-by: Jack Pham <jackp@codeaurora.org>