bindings: rename links to mason USB2/USB3 DT files

Those files got renamed, but another DT file still points to the older
places.

Fixes: 87a55485 ("dt-bindings: phy: meson-g12a-usb3-pcie-phy: convert to yaml")
Fixes: da86d286 ("dt-bindings: phy: meson-g12a-usb2-phy: convert to yaml")
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>