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>