speaker(4): drop NEEDGIANT

When the frequency configuration logic was moved to clock.c in 2008, a
mutex lock was added there (timer_spkr_setfreq) to serialize accesses
to the I/O register.

Since then, no more calls to disable/enable_intr were needed in spkr.c
than they were needed in the other callers to the same timer_spkr
functions in syscons / kern_cons, that is, not at all. This is because
there are no other accesses remaining in the kernel to the i8254
timers after boot than through clock.c.

For context, see commits
e465985885
and
93f5134aaf.

Signed-off-by: Raphael Poss <knz@thaumogen.net>
Reviewed by: imp
Pull Request: https://github.com/freebsd/freebsd-src/pull/1922

sys/dev/speaker/spkr.c

@@ -24,7 +24,7 @@ static	d_ioctl_t	spkrioctl;
 
 static struct cdevsw spkr_cdevsw = {
 	.d_version =	D_VERSION,
-	.d_flags =	D_NEEDGIANT,
+	.d_flags =	0,
 	.d_open =	spkropen,
 	.d_close =	spkrclose,
 	.d_write =	spkrwrite,
@@ -78,10 +78,8 @@ tone(unsigned int thz, unsigned int centisecs)
 	if (timer_spkr_acquire()) {
 		return;
 	}
-	disable_intr();
 	/* Configure the speaker with the tone frequency. */
 	timer_spkr_setfreq(thz);
-	enable_intr();
 
 	/*
 	 * Make the current thread sleep while the tone is being