clk: mmp2: Add clocks for the thermal sensors

The register definitions gotten from OLPC Open Firmware.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Link: https://lkml.kernel.org/r/20200309194254.29009-15-lkundrak@v3.sk
Signed-off-by: Stephen Boyd <sboyd@kernel.org>