USB: OTG: Do not start charging before device enumerates

USB battery charging specification defines that device should
not start charging from SDP (or host port) before connecting
i.e. pulling high data line.
Hence, instead of charging immediately after performing detection,
wait till device configuration is selected by host.

Change-Id: I77dd29d1b4fbb57bc2f4362ef77d6a9c73ab6653
CRs-Fixed: 333556
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>