Add iwn-100 firmware.

The firmware is from the Linux firmware git repository; the intel
licence is the same as other firmware blobs.

Tested: iwn1: <Intel Centrino Wireless-N 100> mem 0xf4800000-0xf4801fff irq 19 at device 0.0 on pci5


git-svn-id: svn+ssh://svn.freebsd.org/base/head@270734 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f