usb: gadget: Don't perform start xfer with USB BAM endpoint

usb_ep_enable() API performs start xfer command in addition to setting
endpoint configuration. USB BAM endpoint is reconfigured with endless
data transfer with msm_ep_queue() API which performs USB start xfer
command. This command fails as already start xfer command is invoked
previously. With this USB BAM related endpoint won't be configured as
endless. Fix this issue by adding endless flag with USB BAM endpoint.

Change-Id: Ib6ceead6d7e8e49e95ef2953e9140a43adffc0cf
Signed-off-by: Mayank Rana <mrana@codeaurora.org>