fs/inode: correct the return value

correct the return value of fs_getfilep() since the
semaphore take may probably fail if the thread canceled

Signed-off-by: chao.an <anchao@xiaomi.com>

fs/inode/fs_files.c

@@ -369,7 +369,7 @@ int fs_getfilep(int fd, FAR struct file **filep)
       _files_semgive(list);
     }
 
-  return OK;
+  return ret;
 }
 
 /****************************************************************************