Optimize ccw screen in subiquity on s390x by filtering for devices relevant at install time

The current subiquity version for s390x presents ALL CCW devices (the special Z systems devices) on one screen based on the output of lszdev.
This includes some devices that are not really relevant at install time, like CTC, LCS and generic-ccw.
Unfortunately lszdev is not perfect at filtering for certain device types, but it allows to either specify _one_ ccw type or _one_ group of ccw types.
( I asked for supporting a _list_ of multiple types/groups upstream: https://github.com/ibm-s390-tools/s390-tools/issues/75 )

But the three (groups of) types (qeth, zfcp <incl. zfcp-lun and zfcp-host> and dasd <incl. dasd-eckd and dasd-fba> cover everything that is relevant at install time.

Hence a suggestion is to replace the single lszdev call by 3 calls like:
lszdev qeth ...
lszdev dasd ...
lszdev zfcp ...
and concatenate the output afterwards.