sound: remove PCM_KLDSTRING() and fix status strings

PCM_KLDSTRING() prints the kernel module associated with a given audio
device only when that module is not compiled in. Get rid of
PCM_KLDSTRING() altogether and print the driver name (even for modules
that are compiled in) instead, as it implies the module as well.

While here, convert all status strings to the following dmesg-like
format:

[<port|mem> <irq>] on <driver>

Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Reviewed by: markj, imp
Differential Revision: https://reviews.freebsd.org/D43349

(cherry picked from commit 837cd192ebf2d0d4f5ded8883403ef11e6fa6438)