Reinstate more aggressive <2% HW error target for avalon-auto

ASIC-README

@@ -94,7 +94,7 @@ Avalon commands:
 
 Avalon auto will enable dynamic overclocking gradually increasing and
 decreasing the frequency till the highest hashrate that keeps hardware errors
-around 1% is achieved. This WILL run your avalon beyond its normal specification
+under 2% is achieved. This WILL run your avalon beyond its normal specification
 so the usual warnings apply. When avalon-auto is enabled, the avalon-options
 for frequency and timeout are used as the starting point only.
 

driver-avalon.c

@@ -916,10 +916,10 @@ static void *avalon_send_tasks(void *userdata)
 				   info->auto_nonces <= (AVALON_AUTO_CYCLE * 21 / 20)) {
 					int total = info->auto_nonces + info->auto_hw;
 
-					/* Try to keep hw errors ~1% */
-					if (info->auto_hw * 200 < total)
+					/* Try to keep hw errors < 2% */
+					if (info->auto_hw * 100 < total)
 						avalon_inc_freq(info);
-					else if (info->auto_hw * 100 > total)
+					else if (info->auto_hw * 66 > total)
 						avalon_dec_freq(info);
 			}
 			avalon_reset_auto(info);