[iwm] Sync if_iwm_phy_db code with Linux iwlwifi.

[ivadasz]

Summary

This dynamically allocates some arrays now, which were statically sized
in the existing code from an older iwlwifi version.

Obtained from: DragonFlyBSD

[adrian]

the rest of the patch looks good. let's just change M_DEVBUF to M_IWM and declare a new malloc type.

sys/dev/iwm/if_iwm_phy_db.c

227

please create a M_IWM malloc type so we can easily track this stuff. Having random device stuff in M_DEVBUF makes tracking leaks suck.