mac80211: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20200707204548.GA9320@embeddedor
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/mesh_hwmp.c b/net/mac80211/mesh_hwmp.c
index 02cde0f..bae3a3e 100644
--- a/net/mac80211/mesh_hwmp.c
+++ b/net/mac80211/mesh_hwmp.c
@@ -1266,7 +1266,7 @@ void mesh_path_tx_root_frame(struct ieee80211_sub_if_data *sdata)
 		break;
 	case IEEE80211_PROACTIVE_PREQ_WITH_PREP:
 		flags |= IEEE80211_PREQ_PROACTIVE_PREP_FLAG;
-		/* fall through */
+		fallthrough;
 	case IEEE80211_PROACTIVE_PREQ_NO_PREP:
 		interval = ifmsh->mshcfg.dot11MeshHWMPactivePathToRootTimeout;
 		target_flags |= IEEE80211_PREQ_TO_FLAG |