usb: dwc3: gadget: update the return value of pullup function

When the controller halt fails we issue a core soft reset. But we
do not update the return value based on the soft reset status. This
can result in sending incorrect return value to UDC core even though
soft reset was successful and will result in aborting the function
disconnect callbacks. Fix this by updating the return value to reflect
the correct status.

Change-Id: I67965824c3ca3ed09da29369d707529a33c3d450
Signed-off-by: Elson Roy Serrao <eserrao@codeaurora.org>