powerpc/mpc85xx: Update TMU device tree node for T1040/T1042

Update #thermal-sensor-cells from 0 to 1 according to the new binding. The
sensor specifier added is the monitoring site ID, and represents the "n" in
TRITSRn and TRATSRn.

Signed-off-by: Jia Hongtao <hongtao.jia@nxp.com>
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>