USB: gadget: udc: clean up an indentation issue

There is a statement that is indented too deeply, remove
the extraneous tabs.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20190927085031.14739-1-colin.king@canonical.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>