Fix SH and AN commands on FT-2000 for VFOB as these commands are not targetable

[mikaelnousiainen]

• The SH and AN commands on FT-2000 are not targetable, so the VFO parameter needs to be always zero.
• Set the number of retries to 3 in FT-2000 backend to follow other Yaesu backends. There should be no need for 10 retries. It seems the commit where the number of retries originates is from 5 years ago and mentions only that Kenwood retries should be increased, so it may be an mistake anyway... These retries will become an issue when the rig is powered off, as it takes a very long time for any command to time out.