docs: fix broken paths to docs/config/ich9-ehci-uhci.cfg
With the move of some docs/ to docs/devel/ on ac06724a71,
a reference path was not updated.
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
authored by