mailmap: add entry for Bence Csókás

I will be leaving Prolan this week.  You can reach me by my personal email
for now.

Link: https://lkml.kernel.org/r/20250915-mailmap-v1-1-9ebdea93c6a7@prolan.hu
Signed-off-by: Bence Csókás <bence98@sch.bme.hu>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: bence98

.mailmap

@@ -134,6 +134,7 @@ Ben M Cahill <ben.m.cahill@intel.com>
 Ben Widawsky <bwidawsk@kernel.org> <ben@bwidawsk.net>
 Ben Widawsky <bwidawsk@kernel.org> <ben.widawsky@intel.com>
 Ben Widawsky <bwidawsk@kernel.org> <benjamin.widawsky@intel.com>
+Bence Csókás <bence98@sch.bme.hu> <csokas.bence@prolan.hu>
 Benjamin Poirier <benjamin.poirier@gmail.com> <bpoirier@suse.de>
 Benjamin Tissoires <bentiss@kernel.org> <benjamin.tissoires@gmail.com>
 Benjamin Tissoires <bentiss@kernel.org> <benjamin.tissoires@redhat.com>