staging: omap-thermal: update DT entry documentation

Simple update on documentation file for DT. This patch
also adds an example for OMAP4430 and 0MAP4470, and also updated
OMAP4460's example.

Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>