Remove %changelog from spec file

Remove the %changelog section from the spec files since it does
not get updated in the master branch. Not only does this mean
the information is stale, but it can result in 'make deb' failing
to build packages, issue #7825. This section should be updated
for tagged releases.

Reviewed-by: Giuseppe Di Natale <guss80@gmail.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #7825
Closes #7827