mailmap: sort entries

to help avoid duplicates (found one)

Signed-off-by: Loic Dachary <loic@dachary.org>
mailmap: Tommi Virtanen is not with Red Hat

The entry was added by s/inktank/redhat/ and did not acknowledge that
Tommi Virtanen left Inktank before it was acquired.

Signed-off-by: Loic Dachary <loic@dachary.org>