trivial: fix an -> a typos in documentation and comments

It is always "an" if there is a vowel _spoken_ (not written).
So it is:
"an hour" (spoken vowel)
but
"a uniform" (spoken 'j')

Signed-off-by: Frederik Schwarzer <schwarzerf@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/cpufreq/Kconfig

@@ -83,7 +83,7 @@ config CPU_FREQ_DEFAULT_GOV_USERSPACE
 	select CPU_FREQ_GOV_USERSPACE
 	help
 	  Use the CPUFreq governor 'userspace' as default. This allows
-	  you to set the CPU frequency manually or when an userspace 
+	  you to set the CPU frequency manually or when a userspace 
 	  program shall be able to set the CPU dynamically without having
 	  to enable the userspace governor manually.
 
@@ -138,7 +138,7 @@ config CPU_FREQ_GOV_USERSPACE
 	tristate "'userspace' governor for userspace frequency scaling"
 	help
 	  Enable this cpufreq governor when you either want to set the
-	  CPU frequency manually or when an userspace program shall
+	  CPU frequency manually or when a userspace program shall
 	  be able to set the CPU dynamically, like on LART 
 	  <http://www.lartmaker.nl/>.