net: Remove bouncing hippi list

linux-hippi is bouncing with:

 <linux-hippi@sunsite.dk>:
 Sorry, no mailbox here by that name. (#5.1.1)

Remove it.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

MAINTAINERS

@@ -10287,7 +10287,6 @@ F:	drivers/input/touchscreen/himax_hx83112b.c
 
 HIPPI
 M:	Jes Sorensen <jes@trained-monkey.org>
-L:	linux-hippi@sunsite.dk
 S:	Maintained
 F:	drivers/net/hippi/
 F:	include/linux/hippidevice.h