dt-bindings: clock: mediatek: add support for MT7623

This patch adds bindings for apmixedsys, audsys, bpsys, ethsys,
hifsys, imgsys, infracfg, mmsys, pericfg, topckgen and vdecsys
for MT6723.

Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>