Use AVA_GETS_OK macro in avalon_read.

driver-avalon.c

@@ -262,7 +262,7 @@ static int avalon_read(int fd, char *buf, ssize_t len)
 		len -= ret;
 	}
 
-	return 0;
+	return AVA_GETS_OK;
 }
 
 static int avalon_reset(struct cgpu_info *avalon, int fd)

driver-avalon.h

@@ -115,8 +115,6 @@ struct avalon_info {
 
 #define AVA_GETS_ERROR -1
 #define AVA_GETS_OK 0
-#define AVA_GETS_RESTART 1
-#define AVA_GETS_TIMEOUT 2
 
 #define AVA_SEND_ERROR -1
 #define AVA_SEND_OK 0