overlays: use all seven dwc2 gadget fifos.

overlays: use all seven dwc2 gadget fifos.

Linux 4.9 needed fifos to be set to their default values,
 leaving the last one (silently) set to zero size.
From 4.12 Linux allows fifos to be set to any size EXCEPT zero.

Resolves https://github.com/raspberrypi/linux/issues/2390

Signed-off-by: John Greb <h3x4m3r0n@gmail.com>
(cherry picked from commit 3d85e84fdc9484f7a78ab3d3e8a04fed817ab576
https://github.com/raspberrypi/linux raspi/rpi-4.15.y)
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>