add patch for debugging NWA50AX Pro issues

patches/openwrt/0007-mac80211-add-patch-for-debug-output-for-NWA50AX-Pro-issues.patch

+From: Nico <github@nicoboehr.de>
+Date: Tue, 12 Sep 2023 17:41:23 +0000
+Subject: mac80211: add patch for debug output for NWA50AX Pro issues
+
+diff --git a/package/kernel/mac80211/patches/build/900-ffs-debug.patch b/package/kernel/mac80211/patches/build/900-ffs-debug.patch
+new file mode 100644
+index 0000000000000000000000000000000000000000..998f2d73c1c072441a0e47ce0c4f9f9870972962
+--- /dev/null
++++ b/package/kernel/mac80211/patches/build/900-ffs-debug.patch
+@@ -0,0 +1,13 @@
++--- a/net/mac80211/sta_info.c
+++++ b/net/mac80211/sta_info.c
++@@ -2363,6 +2363,10 @@ static void sta_stats_decode_rate(struct
++ 
++ 		sband = local->hw.wiphy->bands[band];
++ 
+++		printf("sband = %p, band = 0x%x\n", sband, band);
+++		if (!sband)
+++			break;
+++
++ 		if (WARN_ON_ONCE(!sband->bitrates))
++ 			break;
++