iwlwifi: ignore 0-length PHY DB sections

This can happen during development but can cause problems,
WARN (once) and go on.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Reviewed-by: Guy Cohen <guy.cohen@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/iwlwifi/iwl-phy-db.c

@@ -413,6 +413,9 @@ static int iwl_phy_db_send_all_channel_groups(
 		if (!entry)
 			return -EINVAL;
 
+		if (WARN_ON_ONCE(!entry->size))
+			continue;
+
 		/* Send the requested PHY DB section */
 		err = iwl_send_phy_db_cmd(phy_db,
 					  type,