[components] fixed signed/unsigned mismatch warning

components/drivers/src/pipe.c

@@ -358,7 +358,7 @@ rt_err_t  rt_pipe_close  (rt_device_t device)
 rt_size_t rt_pipe_read   (rt_device_t device, rt_off_t pos, void *buffer, rt_size_t count)
 {
     uint8_t *pbuf;
-    int read_bytes = 0;
+    rt_size_t read_bytes = 0;
     rt_pipe_t *pipe = (rt_pipe_t *)device;
 
     if (device == RT_NULL)
@@ -386,7 +386,7 @@ rt_size_t rt_pipe_read   (rt_device_t device, rt_off_t pos, void *buffer, rt_siz
 rt_size_t rt_pipe_write  (rt_device_t device, rt_off_t pos, const void *buffer, rt_size_t count)
 {
     uint8_t *pbuf;
-    int write_bytes = 0;
+    rt_size_t write_bytes = 0;
     rt_pipe_t *pipe = (rt_pipe_t *)device;
 
     if (device == RT_NULL)

components/finsh/msh.c

@@ -282,7 +282,7 @@ RTM_EXPORT(system);
 static int _msh_exec_cmd(char *cmd, rt_size_t length, int *retp)
 {
     int argc;
-    int cmd0_size = 0;
+    rt_size_t cmd0_size = 0;
     cmd_function_t cmd_func;
     char *argv[RT_FINSH_ARG_MAX];
 
@@ -448,7 +448,7 @@ void msh_auto_complete_path(char *path)
     }
     else
     {
-        int length, min_length;
+        rt_size_t length, min_length;
 
         min_length = 0;
         for (;;)