sound: Make sndstat PVCHAN and RVCHAN nvlist parameters bool

Prior to 02d4eeabfd ("sound: Allocate vchans on-demand"), the
play.vchans and rec.vchans sysctls corresponded to the value of
d->pvchancount and d->rvchancount respectively, which is also what we
are exporting through SNDST_DSPS_SOUND4_PVCHAN and
SNDST_DSPS_SOUND4_RVCHAN respectively. Since that commit, the sysctls
mentioned have been modified to show whether play/rec vchans are enabled
or not. Modify the sndstat nvlist parameters accordingly.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D49980

share/man/man4/sndstat.4

@@ -76,10 +76,10 @@ dsps (NVLIST ARRAY): 1
 		unit (NUMBER): 0
 		status (STRING): on hdaa0
 		bitperfect (BOOL): FALSE
-		pvchan (NUMBER): 1
+		pvchan (BOOL): TRUE
 		pvchanrate (NUMBER): 48000
 		pvchanformat (NUMBER): 0x00000010
-		rvchan (NUMBER): 0
+		rvchan (BOOL): TRUE
 		rvchanrate (NUMBER): 48000
 		rvchanformat (NUMBER): 0x00000010
 		channel_info (NVLIST_ARRAY): 1
@@ -181,13 +181,13 @@ Usually reports the driver the device is attached on.
 .It Dv bitperfect
 Whether the sound card has bit-perfect mode enabled.
 .It Dv pvchan
-Number of playback virtual channels.
+Playback virtual channels enabled.
 .It Dv pvchanrate
 Playback virtual channel sample rate.
 .It Dv pvchanformat
 Playback virtual channel format.
 .It Dv rvchan
-Number of recording virtual channels.
+Recording virtual channels enabled.
 .It Dv rvchanrate
 Recording virtual channel sample rate.
 .It Dv rvchanformat

sys/dev/sound/pcm/sndstat.c

@@ -440,12 +440,14 @@ sndstat_build_sound4_nvlist(struct snddev_info *d, nvlist_t **dip)
 	nvlist_add_string(sound4di, SNDST_DSPS_SOUND4_STATUS, d->status);
 	nvlist_add_bool(
 	    sound4di, SNDST_DSPS_SOUND4_BITPERFECT, d->flags & SD_F_BITPERFECT);
-	nvlist_add_number(sound4di, SNDST_DSPS_SOUND4_PVCHAN, d->pvchancount);
+	nvlist_add_bool(sound4di, SNDST_DSPS_SOUND4_PVCHAN,
+	    d->flags & SD_F_PVCHANS);
 	nvlist_add_number(sound4di, SNDST_DSPS_SOUND4_PVCHANRATE,
 	    d->pvchanrate);
 	nvlist_add_number(sound4di, SNDST_DSPS_SOUND4_PVCHANFORMAT,
 	    d->pvchanformat);
-	nvlist_add_number(sound4di, SNDST_DSPS_SOUND4_RVCHAN, d->rvchancount);
+	nvlist_add_bool(sound4di, SNDST_DSPS_SOUND4_RVCHAN,
+	    d->flags & SD_F_RVCHANS);
 	nvlist_add_number(sound4di, SNDST_DSPS_SOUND4_RVCHANRATE,
 	    d->rvchanrate);
 	nvlist_add_number(sound4di, SNDST_DSPS_SOUND4_RVCHANFORMAT,