MAINTAINERS: Update link for linux-ax25.org

http://linux-ax25.org has been down for nearly a year. Its official
replacement is https://linux-ax25.in-berlin.de. Update all links to the
new URL.

Link: https://marc.info/?m=166792551600315Signed-off-by: Peter Lafreniere <peter@n8pjl.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>

MAINTAINERS

@@ -3344,7 +3344,7 @@ AX.25 NETWORK LAYER
 M:	Ralf Baechle <ralf@linux-mips.org>
 L:	linux-hams@vger.kernel.org
 S:	Maintained
-W:	http://www.linux-ax25.org/
+W:	https://linux-ax25.in-berlin.de
 F:	include/net/ax25.h
 F:	include/uapi/linux/ax25.h
 F:	net/ax25/
@@ -14756,7 +14756,7 @@ NETROM NETWORK LAYER
 M:	Ralf Baechle <ralf@linux-mips.org>
 L:	linux-hams@vger.kernel.org
 S:	Maintained
-W:	http://www.linux-ax25.org/
+W:	https://linux-ax25.in-berlin.de
 F:	include/net/netrom.h
 F:	include/uapi/linux/netrom.h
 F:	net/netrom/
@@ -18607,7 +18607,7 @@ ROSE NETWORK LAYER
 M:	Ralf Baechle <ralf@linux-mips.org>
 L:	linux-hams@vger.kernel.org
 S:	Maintained
-W:	http://www.linux-ax25.org/
+W:	https://linux-ax25.in-berlin.de
 F:	include/net/rose.h
 F:	include/uapi/linux/rose.h
 F:	net/rose/