fixes a crash on Android 6.0.1 due to invalid theme attribute
fixes a crash on Android 6.0.1 due to invalid theme attribute

NordicSemiconductor/Android-nRF-Toolbox,NordicSemiconductor/Android-nRF-Toolbox,NordicSemiconductor/Android-nRF-Toolbox,NordicSemiconductor/Android-nRF-Toolbox