ALSA: Add missing dependency on CONFIG_SND_TIMER

Since the build of PCM timer may be disabled via Kconfig now, each
driver that provides a timer interface needs to set CONFIG_SND_TIMER
explicitly.  Otherwise it may get a build error due to missing
symbol.

Fixes: 90bbaf66ee7b ('ALSA: timer: add config item to export PCM timer disabling for expert')
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Cc: <stable@vger.kernel.org> # v4.4+
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/sparc/Kconfig b/sound/sparc/Kconfig
index d75deba..dfcd386 100644
--- a/sound/sparc/Kconfig
+++ b/sound/sparc/Kconfig
@@ -22,6 +22,7 @@
 config SND_SUN_CS4231
 	tristate "Sun CS4231"
 	select SND_PCM
+	select SND_TIMER
 	help
 	  Say Y here to include support for CS4231 sound device on Sun.