usb: dwc3: gadget: Ignore ENDXFER completion for GSI endpoints

GSI endpoints do not generate a completion event for endxfer commands.
Upstream added a check for this event completion before continuing the
clear endpoint halt sequence.  Since this does not happen, skip the
check and continue with the clear halt command.

Change-Id: I082289dfb5ca23f48f794ec92f175ef7a4c830fb
Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
Signed-off-by: Srinivasarao P <spathi@codeaurora.org>