powerpc/85xx: TQM85xx: correct address of LM75 I2C device nodes

Commit 0f73a449 added I2C device nodes
for the LM75 thermal sensor on the TQM85xx modules, unfortunately with
the wrong I2C address. The LM75s are located at address 0x48.

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