优化ymodem升级超时

ymodem/ymodem.h

@@ -12,7 +12,7 @@
 #define PACKET_OVERHEAD         (PACKET_HEADER + PACKET_TRAILER)
 #define PACKET_SIZE             (128)
 #define PACKET_1K_SIZE          (1024)
-#define PACKET_TIMEOUT          (1000)  /* milliseconds */
+#define PACKET_TIMEOUT          (3000)  /* milliseconds */
 
 #define FILE_NAME_LENGTH (64)
 #define FILE_SIZE_LENGTH (16)