mailmap: Fix BALATON Zoltan author email

This fixes authorship of commits 5cbd51a and friends, where the
qemu-ppc mailing list rewrote the "From:" field in the corresponding
patches.  See commit 3bd2608 ("maint: Add .mailmap entries for
patches claiming list authorship") for explanation.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230927143815.3397386-8-eblake@redhat.com>

.mailmap

@@ -59,6 +59,7 @@ Julia Suvorova <jusual@mail.ru> Julia Suvorova via Qemu-devel <qemu-devel@nongnu
 Justin Terry (VM) <juterry@microsoft.com> Justin Terry (VM) via Qemu-devel <qemu-devel@nongnu.org>
 Stefan Weil <sw@weilnetz.de> Stefan Weil via <qemu-devel@nongnu.org>
 Andrey Drobyshev <andrey.drobyshev@virtuozzo.com> Andrey Drobyshev via <qemu-block@nongnu.org>
+BALATON Zoltan <balaton@eik.bme.hu> BALATON Zoltan via <qemu-ppc@nongnu.org>
 
 # Next, replace old addresses by a more recent one.
 Aleksandar Markovic <aleksandar.qemu.devel@gmail.com> <aleksandar.markovic@mips.com>