USB: msm_otg: Fix data contact detection issue

Data contact detection (DCD) involves applying small amount of current on
D+ and waiting for it to go low.  The D+ is pulled to low when the data
pins get contacted with the other device data pins.

The current code does not disable D+ pull-down resistor during DCD. If this
resistor is not disabled, the current applied on D+ becomes low immediately
even without connecting to any device.  Fix it.  Remove enable_dcd flag
from platform data as data contact detection is working reliably on all
targets supported by this driver.

Change-Id: I1d2a622fc4b7622ebb3b33746a8a8d9361e01e57
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>