sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

iwm(4): Remove _mvm from the namespace.

This was inherited from iwlwifi, which drives devices supported by both
iwn(4) and iwm(4) in FreeBSD. In iwm(4) _mvm is meaningless, so remove
it. OpenBSD made the same change a long time ago. No functional change
intended.

MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation

[iwm] Move Smart Fifo handling into if_iwm_sf.c, sync with Linux iwlwifi.

* This change also fixes a possible issue in the existing smart-fifo code,
which set the IWM_SF_CFG_DUMMY_NOTIF_OFF bit on AC8260 chipsets, although
that's only used in iwlwifi for Family 8000 chipsets connected via SDIO
interface.

Obtained from: Dragonflybsd.git cb650b01526b0aeef3c4307d926e7f1428997d50