When multiple adapters are present in the system, pci hot-removing second
adapter leads to the following warning as both the adapters registered
thermal zone device with same thermal zone name/type.
Therefore, use unique thermal zone name during thermal zone device
initialization. Also mark thermal zone dev NULL once unregistered.

[  414.370143] ------------[ cut here ]------------
[  414.370944] sysfs group 'power' not found for kobject 'hwmon0'
[  414.371747] WARNING: CPU: 9 PID: 2661 at fs/sysfs/group.c:281
 sysfs_remove_group+0x76/0x80
[  414.382550] CPU: 9 PID: 2661 Comm: bash Not tainted 5.8.0-rc6+ #33
[  414.383593] Hardware name: Supermicro X10SRA-F/X10SRA-F, BIOS 2.0a 06/23/2016
[  414.384669] RIP: 0010:sysfs_remove_group+0x76/0x80
[  414.385738] Code: 48 89 df 5b 5d 41 5c e9 d8 b5 ff ff 48 89 df e8 60 b0 ff ff
 eb cb 49 8b 14 24 48 8b 75 00 48 c7 c7 90 ae 13 bb e8 6a 27 d0 ff <0f> 0b 5b 5d
 41 5c c3 0f 1f 00 0f 1f 44 00 00 48 85 f6 74 31 41 54
[  414.388404] RSP: 0018:ffffa22bc080fcb0 EFLAGS: 00010286
[  414.389638] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[  414.390829] RDX: 0000000000000001 RSI: ffff8ee2de3e9510 RDI: ffff8ee2de3e9510
[  414.392064] RBP: ffffffffbaef2ee0 R08: 0000000000000000 R09: 0000000000000000
[  414.393224] R10: 0000000000000000 R11: 000000002b30006c R12: ffff8ee260720008
[  414.394388] R13: ffff8ee25e0a40e8 R14: ffffa22bc080ff08 R15: ffff8ee2c3be5020
[  414.395661] FS:  00007fd2a7171740(0000) GS:ffff8ee2de200000(0000)
 knlGS:0000000000000000
[  414.396825] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  414.398011] CR2: 00007f178ffe5020 CR3: 000000084c5cc003 CR4: 00000000003606e0
[  414.399172] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  414.400352] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  414.401473] Call Trace:
[  414.402685]  device_del+0x89/0x400
[  414.403819]  device_unregister+0x16/0x60
[  414.405024]  hwmon_device_unregister+0x44/0xa0
[  414.406112]  thermal_remove_hwmon_sysfs+0x196/0x200
[  414.407256]  thermal_zone_device_unregister+0x1b5/0x1f0
[  414.408415]  cxgb4_thermal_remove+0x3c/0x4f [cxgb4]
[  414.409668]  remove_one+0x212/0x290 [cxgb4]
[  414.410875]  pci_device_remove+0x36/0xb0
[  414.412004]  device_release_driver_internal+0xe2/0x1c0
[  414.413276]  pci_stop_bus_device+0x64/0x90
[  414.414433]  pci_stop_and_remove_bus_device_locked+0x16/0x30
[  414.415609]  remove_store+0x75/0x90
[  414.416790]  kernfs_fop_write+0x114/0x1b0
[  414.417930]  vfs_write+0xcf/0x210
[  414.419059]  ksys_write+0xa7/0xe0
[  414.420120]  do_syscall_64+0x4c/0xa0
[  414.421278]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  414.422335] RIP: 0033:0x7fd2a686afd0
[  414.423396] Code: Bad RIP value.
[  414.424549] RSP: 002b:00007fffc1446148 EFLAGS: 00000246 ORIG_RAX:
 0000000000000001
[  414.425638] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fd2a686afd0
[  414.426830] RDX: 0000000000000002 RSI: 00007fd2a7196000 RDI: 0000000000000001
[  414.427927] RBP: 00007fd2a7196000 R08: 000000000000000a R09: 00007fd2a7171740
[  414.428923] R10: 00007fd2a7171740 R11: 0000000000000246 R12: 00007fd2a6b43400
[  414.430082] R13: 0000000000000002 R14: 0000000000000001 R15: 0000000000000000
[  414.431027] irq event stamp: 76300
[  414.435678] ---[ end trace 13865acb4d5ab00f ]---

Fixes: b1871915 ("cxgb4: Add thermal zone support")
Signed-off-by: Potnuri Bharat Teja <bharat@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>