lantiq: Add sensible hw-defaults for dwc2

Lantiq driver does not work with autodetected fifo sizes so use ones
from original ltq-hcd driver in dwc2. Other values can be
autodetected.

Signed-off-by: Antti Seppälä <a.seppala@gmail.com>
Signed-off-by: Vincent Pelletier <plr.vincent@gmail.com>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@44674 3c298f89-4303-0410-b956-a3cf2f4a3e73