atm: idt77252: fix kmemleak when rmmod idt77252

There are memory leaks reported by kmemleak:

unreferenced object 0xffff888106500800 (size 128):
comm "modprobe", pid 1017, jiffies 4297787785 (age 67.152s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<00000000970ce626>] __kmem_cache_alloc_node+0x20c/0x380
[<00000000fb5f78d9>] kmalloc_trace+0x2f/0xb0
[<000000000e947e2a>] idt77252_init_one+0x2847/0x3c90 [idt77252]
[<000000006efb048e>] local_pci_probe+0xeb/0x1a0
...

unreferenced object 0xffff888106500b00 (size 128):
comm "modprobe", pid 1017, jiffies 4297787785 (age 67.152s)
hex dump (first 32 bytes):
00 20 3d 01 80 88 ff ff 00 20 3d 01 80 88 ff ff . =...... =.....
f0 23 3d 01 80 88 ff ff 00 20 3d 01 00 00 00 00 .#=...... =.....
backtrace:
[<00000000970ce626>] __kmem_cache_alloc_node+0x20c/0x380
[<00000000fb5f78d9>] kmalloc_trace+0x2f/0xb0
[<00000000f451c5be>] alloc_scq.constprop.0+0x4a/0x400 [idt77252]
[<00000000e6313849>] idt77252_init_one+0x28cf/0x3c90 [idt77252]

The root cause is traced to the vc_maps which alloced in open_card_oam()
are not freed in close_card_oam(). The vc_maps are used to record
open connections, so when close a vc_map in close_card_oam(), the memory
should be freed. Moreover, the ubr0 is not closed when close a idt77252
device, leading to the memory leak of vc_map and scq_info.

Fix them by adding kfree in close_card_oam() and implementing new
close_card_ubr0() to close ubr0.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Li Zetao <[e-mail]>
Reviewed-by: Francois Romieu <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/atm/idt77252.c

···
 
 				recycle_rx_pool_skb(card, &vc->rcv.rx_pool);
 			}
+			kfree(vc);
 		}
 	}
 }
···
 	clear_bit(VCF_IDLE, &vc->flags);
 	writel(TCMDQ_START | 0, SAR_REG_TCMDQ);
 	return 0;
+}
+
+static void
+close_card_ubr0(struct idt77252_dev *card)
+{
+	struct vc_map *vc = card->vcs[0];
+
+	free_scq(card, vc->scq);
+	kfree(vc);
 }
 
 static int
···
 	struct idt77252_dev *card = dev->dev_data;
 	u32 conf;
 
+	close_card_ubr0(card);
 	close_card_oam(card);
 
 	conf = SAR_CFG_RXPTH |	/* enable receive path           */