usb: gadget: Do not take BKL for gadget->ops->ioctl

There is no gadget driver in the tree that
actually implements the ioctl operation, so
obviously it is not necessary to hold the
BKL around the call.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Michał Nazarewicz <m.nazarewicz@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>