[iwm] Add support for iwm 3168 cards

```
iwm0@pci0:5:0:0: class=0x028000 card=0x21108086 chip=0x24fb8086
rev=0x10 hdr=0x00
vendor = 'Intel Corporation'
device = 'Dual Band Wireless-AC

[iwm] Add support for iwm 3168 cards

```
iwm0@pci0:5:0:0: class=0x028000 card=0x21108086 chip=0x24fb8086
rev=0x10 hdr=0x00
vendor = 'Intel Corporation'
device = 'Dual Band Wireless-AC 3168NGW [Stone Peak]'
class = network
[94829] iwm0: <Intel(R) Dual Band Wireless AC 3168> mem
0xef700000-0xef701fff at device 0.0 on pci5
[94829] iwm0: hw rev 0x220, fw ver 22.361476.0, address
28:c6:3f:15:43:c5
```

MFC After: 2 weeks
Reviewed by: ivadasz (over IRC)
PR: 224886
Differential Revision: https://reviews.freebsd.org/D14865

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