staging: omap-thermal: remove dedicated counter register for OMAP5

On OMAP54xx there is only one counter register. For this reason,
each domain must use the same counter register. This patch changes
the data definition to coupe with this.

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