USB: gadget: ci13xx_udc: Fix bug in halting a control endpoint

A new setup packet can arrive on the control endpoint exactly when
software tries to halt it.  The halt condition will continue to be
cleared by the hardware.  The current code is ignoring this scenario
and polling for the halt condition to be true.  Return success from
ep_set_halt upon a new setup packet arrival.

Change-Id: If431f84b4e6f50e706520bb08e6ff5f6cc5fd759
CRs-fixed: 299838
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>