ALSA: timer: fix SND_PCM_TIMER Kconfig text

Fix spelling and typos for SND_PCM_TIMER.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/Kconfig

@@ -97,11 +97,11 @@ config SND_PCM_TIMER
 	bool "PCM timer interface" if EXPERT
 	default y
 	help
-	  If you disable this option, pcm timer will be inavailable, so
+	  If you disable this option, pcm timer will be unavailable, so
-	  those stubs used pcm timer (e.g. dmix, dsnoop & co) may work
+	  those stubs that use pcm timer (e.g. dmix, dsnoop & co) may work
 	  incorrectlly.
 
-	  For some embedded device, we may disable it to reduce memory
+	  For some embedded devices, we may disable it to reduce memory
 	  footprint, about 20KB on x86_64 platform.
 
 config SND_SEQUENCER_OSS