arm: dts: mt2701: Add clock controller device nodes

Add clock controller nodes for MT2701, include topckgen, infracfg,
pericfg and apmixedsys. This patch also add two oscillators that
provide clocks for MT2701.

Signed-off-by: James Liao <jamesjj.liao@mediatek.com>
Signed-off-by: Erin Lo <erin.lo@mediatek.com>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>