dt-bindings: marvell,mmp2: Add clock ids for the thermal sensors

There seems to be a single thermal sensor block on MMP2 and a couple
more on MMP3. Add definitions for their respective clocks.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Link: https://lkml.kernel.org/r/20200309194254.29009-14-lkundrak@v3.sk
Signed-off-by: Stephen Boyd <sboyd@kernel.org>