staging: omap-thermal: introduce new features of OMAP54xx

On OMAP54xx ES2.0 there are new features inside the bandgap
device. This patch introduces the registers definition
to access these features and adapts the data structures
to map these new registers. The new features are:

. SIDLE mode
. Cumulative register
. History buffer.
. Buffer freeze bit
. Buffer clear bit

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