CREDITS: update Johannes Berg's gpg key

I've had a new key for almost two years and
revoked the old one, but forgot to update it
here.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

CREDITS

@@ -328,7 +328,7 @@ S: Haifa, Israel
 N: Johannes Berg
 E: johannes@sipsolutions.net
 W: http://johannes.sipsolutions.net/
-P: 1024D/9AB78CA5 AD02 0176 4E29 C137 1DF6 08D2 FC44 CF86 9AB7 8CA5
+P: 4096R/7BF9099A C0EB C440 F6DA 091C 884D  8532 E0F3 73F3 7BF9 099A
 D: powerpc & 802.11 hacker
 
 N: Stephen R. van den Berg (AKA BuGless)