net: lwm2m: temp_sensor: fix min/max measurement values
net: lwm2m: temp_sensor: fix min/max measurement values

Initial values for the min/max measurements were 0 and this caused
issues with sensors maximums that weren't above 0 and minimums that
went below 0.  Let's update those to MAX_INT so the first sensor
value update will set those to correct values.

When resetting the measured values, let's use the current sensor
value not 0.

Signed-off-by: Michael Scott <087571639a1dbb4ff1803c64e3643475ba482686@linaro.org>

Vudentz/zephyr,aceofall/zephyr-iotos,GiulianoFranchetto/zephyr,punitvara/zephyr,galak/zephyr,mbolivar/zephyr,kraj/zephyr,explora26/zephyr,Vudentz/zephyr,mbolivar/zephyr,aceofall/zephyr-iotos,kraj/zephyr,punitvara/zephyr,explora26/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,finikorg/zephyr,punitvara/zephyr,explora26/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,mbolivar/zephyr,zephyriot/zephyr,GiulianoFranchetto/zephyr,GiulianoFranchetto/zephyr,aceofall/zephyr-iotos,nashif/zephyr,finikorg/zephyr,ldts/zephyr,ldts/zephyr,kraj/zephyr,zephyriot/zephyr,zephyriot/zephyr,ldts/zephyr,explora26/zephyr,explora26/zephyr,Vudentz/zephyr,nashif/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,galak/zephyr,punitvara/zephyr,aceofall/zephyr-iotos,kraj/zephyr,galak/zephyr,zephyriot/zephyr,mbolivar/zephyr,zephyrproject-rtos/zephyr,kraj/zephyr,zephyrproject-rtos/zephyr,punitvara/zephyr,GiulianoFranchetto/zephyr,mbolivar/zephyr,nashif/zephyr,Vudentz/zephyr,galak/zephyr,nashif/zephyr,finikorg/zephyr,galak/zephyr,aceofall/zephyr-iotos,ldts/zephyr,zephyriot/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr