tools: ratbagctl: only warn that no devices are available in list_devices
tools: ratbagctl: only warn that no devices are available in list_devices

If the other commands try to access a node, there will be an other error
("Unable to find device X"). So there is no points in having this as a
global check.

For the .devel and .test versions, we are guaranteed to have the
test_device at least, so no worries on this side too.

Signed-off-by: Benjamin Tissoires <7a0e50e3f6a0939db82b6a8a423c08a163896f41@gmail.com>

libratbag/libratbag,libratbag/libratbag,whot/libratbag,libratbag/libratbag,whot/libratbag,whot/libratbag