MAINTAINERS: exec: Mark Kees as maintainer

It's more accurate to mark myself as a maintainer: I've been keeping the
tree up to date in linux-next, etc.

Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Eric W. Biederman <[email protected]>
Signed-off-by: Kees Cook <[email protected]>

Author: kees

MAINTAINERS

@@ -8488,8 +8488,8 @@ F:	rust/kernel/net/phy.rs
 F:	rust/kernel/net/phy/reg.rs
 
 EXEC & BINFMT API, ELF
+M:	Kees Cook <[email protected]>
 R:	Eric Biederman <[email protected]>
-R:	Kees Cook <[email protected]>
 L:	[email protected]
 S:	Supported
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/execve