powerpc/85xx: TQM85xx - add i2c device nodes for LM75

Automatic I2C device probing is not done any more. Therefore we need
proper DTS device node definitions for the I2C LM75 thermal sensor on
the TQM85xx modules.

Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>