There's currently no limit on wiphy names, other than netlink
message size and memory limitations, but that causes issues when,
for example, the wiphy name is used in a uevent, e.g. in rfkill
where we use the same name for the rfkill instance, and then the
buffer there is "only" 2k for the environment variables.

This was reported by syzkaller, which used a 4k name.

Limit the name to something reasonable, I randomly picked 128.

Reported-by:  <syzbot+230d9e642a85d3fec29c@syzkaller.appspotmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>