idevicedebug: Only decode response if not OK, otherwise it may cause a buffer overrun

Only decode the response if it's not OK, otherwise the O in "OK" can be
interpreted as a hexadecimal and cause a buffer overrun.
diff --git a/tools/idevicedebug.c b/tools/idevicedebug.c
index 437faba..b0198a8 100644
--- a/tools/idevicedebug.c
+++ b/tools/idevicedebug.c
@@ -501,7 +501,9 @@
 
 				if (response) {
 					log_debug("response: %s", response);
-					dres = debugserver_client_handle_response(debugserver_client, &response, 1);
+					if (strncmp(response, "OK", 2)) {
+						dres = debugserver_client_handle_response(debugserver_client, &response, 1);
+					}
 				}
 
 				sleep(1);