mailmap: Update email address

My Netronome address is no longer active. I am no maintainer, but
get_maintainer.pl sometimes returns my name for a small number of
files (BPF-related). Add an entry to .mailmap for good measure.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200226171353.18982-1-quentin@isovalent.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

.mailmap

@@ -225,6 +225,7 @@ Pratyush Anand <pratyush.anand@gmail.com> <pratyush.anand@st.com>
 Praveen BP <praveenbp@ti.com>
 Punit Agrawal <punitagrawal@gmail.com> <punit.agrawal@arm.com>
 Qais Yousef <qsyousef@gmail.com> <qais.yousef@imgtec.com>
+Quentin Monnet <quentin@isovalent.com> <quentin.monnet@netronome.com>
 Quentin Perret <qperret@qperret.net> <quentin.perret@arm.com>
 Rafael J. Wysocki <rjw@rjwysocki.net> <rjw@sisk.pl>
 Rajesh Shah <rajesh.shah@intel.com>