fs: 9p: remove unneeded variable

Fix the following coccicheck review:
./fs/9p/vfs_file.c: 117: 5-8: Unneeded variable

Remove unneeded variable used to store return value.

Link: https://lkml.kernel.org/r/20211109114343.132844-1-deng.changcheng@zte.com.cnReported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Changcheng Deng <deng.changcheng@zte.com.cn>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>

fs/9p/vfs_file.c

@@ -114,7 +114,6 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 
 static int v9fs_file_lock(struct file *filp, int cmd, struct file_lock *fl)
 {
-	int res = 0;
 	struct inode *inode = file_inode(filp);
 
 	p9_debug(P9_DEBUG_VFS, "filp: %p lock: %p\n", filp, fl);
@@ -124,7 +123,7 @@ static int v9fs_file_lock(struct file *filp, int cmd, struct file_lock *fl)
 		invalidate_mapping_pages(&inode->i_data, 0, -1);
 	}
 
-	return res;
+	return 0;
 }
 
 static int v9fs_file_do_lock(struct file *filp, int cmd, struct file_lock *fl)