Add deprecation notices to ISA sound cards

ISA sound cards (and ISA itself) are long obsolete. NYCBUG dmesgd has
no entries for any of these devices after 2005.

Mail to -current and -stable revealed some nostalgic interest, but
no offers to test or requests to pospone the deprecation.

Add deprecation notices to device attach routines and man pages for:

snd_ad1816 Analog Devices AD1816 SoundPort
snd_ess Ensoniq ESS
snd_gusc Gravis UltraSound (MAX and newer AFAIK)
snd_mss Microsoft Sound System
snd_sbc Creative Sound Blaster

Reviewed by: cy, mav
MFC after: 3 days
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D34604

(cherry picked from commit e39ec8933be4d6e74cfb32680fb3e67469e66bb7)
(cherry picked from commit d7620b6ec941fc6239bb2600495c2978181cfe28)