USB: gadget: Fix endpoint representation in ci13xxx_udc

Fix a bug where only half the number of endpoints supported by the
hardware are exposed to gadget.  If DEN filed in the DCCPARAMS
register has 'N' then 'N' IN endpoints and 'N" OUT endpoints can be
supported.  But only 'N' bidirectional endpoints are added to the
gadget ep_list.  This patch also ensures that the data and handshake
transactions of previous setup packet are flushed upon a new setup
packet arrival on ep0.

Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>