Nicer printing of Edfa elements when parameters are None
Nicer printing of Edfa elements when parameters are None

When delta_p or target_pch_out_db is None (resulting e.g. from
operating in gain mode) the current logic replaces a whole printed
line with 'None' which does not look very nice in the script outputs.
With this patch, the parameter information is kept in the printout
like this:

  Delta_P (dB):           None
  target pch (dBm):       None

Change-Id: Ie52ce7353a708a174cf9d769918a6136eefbf444
Signed-off-by: Jonas Mårtensson <9c18489050b439bcd0a9df0d47735ceb99443dbb@ri.se>
Fixes: 225cafa8 (Floating point formatting of elements' operational parameters)

Telecominfraproject/gnpy