cifs: Fix memory leak on the deferred close

xfstests on smb21 report kmemleak as below:

unreferenced object 0xffff8881767d6200 (size 64):
comm "xfs_io", pid 1284, jiffies 4294777434 (age 20.789s)
hex dump (first 32 bytes):
80 5a d0 11 81 88 ff ff 78 8a aa 63 81 88 ff ff .Z......x..c....
00 71 99 76 81 88 ff ff 00 00 00 00 00 00 00 00 .q.v............
backtrace:
[<00000000ad04e6ea>] cifs_close+0x92/0x2c0
[<0000000028b93c82>] __fput+0xff/0x3f0
[<00000000d8116851>] task_work_run+0x85/0xc0
[<0000000027e14f9e>] do_exit+0x5e5/0x1240
[<00000000fb492b95>] do_group_exit+0x58/0xe0
[<00000000129a32d9>] __x64_sys_exit_group+0x28/0x30
[<00000000e3f7d8e9>] do_syscall_64+0x35/0x80
[<00000000102e8a0b>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

When cancel the deferred close work, we should also cleanup the struct
cifs_deferred_close.

Fixes: 9e992755be8f2 ("cifs: Call close synchronously during unlink/rename/lease break.")
Fixes: e3fc065682ebb ("cifs: Deferred close performance improvements")
Cc: [e-mail]
Reviewed-by: Shyam Prasad N <[e-mail]>
Signed-off-by: Zhang Xiaoxu <[e-mail]>
Signed-off-by: Steve French <[e-mail]>

fs/cifs/misc.c

···
 	list_for_each_entry(cfile, &cifs_inode->openFileList, flist) {
 		if (delayed_work_pending(&cfile->deferred)) {
 			if (cancel_delayed_work(&cfile->deferred)) {
+				cifs_del_deferred_close(cfile);
+
 				tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 				if (tmp_list == NULL)
 					break;
···
 	list_for_each_entry(cfile, &tcon->openFileList, tlist) {
 		if (delayed_work_pending(&cfile->deferred)) {
 			if (cancel_delayed_work(&cfile->deferred)) {
+				cifs_del_deferred_close(cfile);
+
 				tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 				if (tmp_list == NULL)
 					break;
···
 		if (strstr(full_path, path)) {
 			if (delayed_work_pending(&cfile->deferred)) {
 				if (cancel_delayed_work(&cfile->deferred)) {
+					cifs_del_deferred_close(cfile);
+
 					tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 					if (tmp_list == NULL)
 						break;