MAINTAINERS: step down as netfilter maintainer

I do not feel that I'm up to the task anymore.

I hope this to be a temporary emergeny measure, but for now I'm sure this
is the best course of action for me.

Signed-off-by: Florian Westphal <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

MAINTAINERS

···
 NETFILTER
 M:	Pablo Neira Ayuso <[e-mail]>
 M:	Jozsef Kadlecsik <[e-mail]>
-M:	Florian Westphal <[e-mail]>
 L:	[e-mail]
 L:	[e-mail]
 S:	Maintained