usb: gadget: Fix problem with disable/enable RNDIS interface

RNDIS interface would not get IP after disable/enable via device
manager. The problem was due to non-reset of the trigger with the IPA
in this flow and the fact that infinite transfers were not stopped.
In this change we reset the trigger and remove the infinite transfers.

CRs-fixed:  673591
Change-Id: I434c47796f00e0abbda2b8945e72fcd9c1add644
Signed-off-by: Lena Salman <esalman@codeaurora.org>