Simplify scanning and use correct receive channel

This simplifies the scanning a bit by removing the end_scan which is
not necessary. It also makes use of the channel switch command instead
of using start scan on every channel.

Reorders the 2.4Ghz channels to that the hw_values are correct
and possible to use.

Signed-off-by: Olof Johansson <dev@skyshaper.net>