usb: composite: Draw current based on speed upon resume

If usb device goes to suspend in high speed mode and resumed
back, it is drawing 900mA. Fix this issue by checking gadget
speed before calling usb_gadget_vbus_draw().

Change-Id: I8e94811597084fce015951bd27cc65dec3ae91ff
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>