staging: omap-thermal: make a omap_bandgap_power with only one exit point

Change the way the omap_bandgap_power is written so that it has only
one exit entry (Documentation/CodingStyle).

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