staging: omap-thermal: bandgap: fix setting of alert thresholds

There was an error in check for the valid temperature in
function temp_to_adc_conversion. The temperature value was
compared with higher limit for less than condition as well,
resulting in returning -EINVAL. Corrected the check condition
to properly check for lower and higher temperature limits.

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