MFH: r520276

• According to @koobs the dependency on pyephem/ephem is spurious hence removed.
• When gnuradio was first imported into the tree, UHD (Ettus) was pretty much the only viable high speed device for it. This is no longer true so default option removed.
• Noted plist problem with removed UHD corrected.

PR: ports/240546
Reported by: w.schwarzenfeld@utanet.at

Approved by: portmgr (joneum)