MAINTAINERS: remove Iurii Zaikin from proc sysctl

Iurii Zaikin has moved on to other projects and has had no time to
help with proc sysctl maintenance.
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

MAINTAINERS

@@ -17360,7 +17360,6 @@ F:	tools/testing/selftests/proc/
 PROC SYSCTL
 M:	Luis Chamberlain <mcgrof@kernel.org>
 M:	Kees Cook <keescook@chromium.org>
-M:	Iurii Zaikin <yzaikin@google.com>
 L:	linux-kernel@vger.kernel.org
 L:	linux-fsdevel@vger.kernel.org
 S:	Maintained