wifi: cfg80211: define and use wiphy guard

wifi: cfg80211: define and use wiphy guard

Define a guard for the wiphy mutex, and use it in
most code in cfg80211, though not all due to some
interaction with RTNL and/or indentation.

Suggested-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Reviewed-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://patch.msgid.link/20241122094225.88765cbaab65.I610c9b14f36902e75e1d13f0db29f8bef2298804@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>