MAINTAINERS: ipv6: retire Hideaki Yoshifuji

We very rarely hear from Hideaki Yoshifuji and the IPv4/IPv6
entry covers a lot of code. Asking people to CC someone who
rarely responds feels wrong.

Note that Hideaki Yoshifuji already has an entry in CREDITS
for IPv6 so not adding another one.

Cc: Hideaki YOSHIFUJI <[email protected]>
Signed-off-by: Jakub Kicinski <[email protected]>

Author: kuba-moo

MAINTAINERS

@@ -14598,7 +14598,6 @@ F:	tools/testing/selftests/net/ipsec.c
 
 NETWORKING [IPv4/IPv6]
 M:	"David S. Miller" <[email protected]>
-M:	Hideaki YOSHIFUJI <[email protected]>
 M:	David Ahern <[email protected]>
 L:	[email protected]
 S:	Maintained