fix(discovery): allow networkport update from discovery only for printer

[stonebuzz]

allow networkport update from discovery only for printer

Usefull when printer changes IP

Only network information are deleted (is the goal) other inforamtions , page counter, Sysdescr, serial number, model , manufacturer are still present .

Q	A
Bug fix?	yes/no
New feature?	yes/no
BC breaks?	no
Deprecations?	no
Tests pass?	yes
Fixed tickets	#192