[ath_hal] add a comment for the channel 144 regdomain flag.

I'm .. still trying to figure out what's going on.

sys/dev/ath/ath_hal/ah_regdomain.c

@@ -548,6 +548,14 @@ add_chanlist_mode(struct ath_hal *ah, struct ieee80211_channel chans[],
 			continue;
 		}
 #endif
+
+		/*
+		 * XXX TODO: handle REG_EXT_FCC_CH_144.
+		 *
+		 * Figure out which instances/uses cause us to not
+		 * be allowed to use channel 144 (pri or sec overlap.)
+		 */
+
 		bfreq_lo = MAX(fband->lowChannel + low_adj, freq_lo);
 		bfreq_hi = MIN(fband->highChannel + hi_adj, freq_hi);
 		if (fband->channelSep >= channelSep)