ALSA: Drop leftover snd-rtctimer stuff from Makefile

[ Upstream commit 4df4971 ]

We forgot to remove the line for snd-rtctimer from Makefile while
dropping the functionality.  Get rid of the stale line.

Fixes: 34ce71a ("ALSA: timer: remove legacy rtctimer")
Link: https://lore.kernel.org/r/20240221092156.28695-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

sound/core/Makefile

@@ -33,7 +33,6 @@ snd-ctl-led-objs  := control_led.o
 snd-rawmidi-objs  := rawmidi.o
 snd-timer-objs    := timer.o
 snd-hrtimer-objs  := hrtimer.o
-snd-rtctimer-objs := rtctimer.o
 snd-hwdep-objs    := hwdep.o
 snd-seq-device-objs := seq_device.o