Potentially fix showing battery on desktops

The battery indicator should only be shown on devices with a battery
power supply. It should not be shown when a wireless USB device is
attached that happens to have a battery. This patch potentially fixes
the issue of showing a 0% battery reading on desktops.

system-info/system-info-Linux.sh

@@ -28,7 +28,7 @@ else
   }
 fi
 
-if [[ "$(acpi -b 2>&1 /dev/null)" != "No support for device type: power_supply" ]]; then
+if upower -e | grep 'BAT' 2> /dev/null; then
   function get_battery {
     local output=$(acpi -b)
     local charging=$(echo $output | awk '{ print $3 }')