usb: dwc2: gadget: fix checkpatch errors

Fix checkpatch errors as belows.

  ERROR: open brace '{' following function declarations go on the next line
  ERROR: space required before the open parenthesis '('

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Acked-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>