It's UTF-8

Fix some comments to "UTF-8".

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
diff --git a/fs/nls/Kconfig b/fs/nls/Kconfig
index 0ab8f00..976eccc 100644
--- a/fs/nls/Kconfig
+++ b/fs/nls/Kconfig
@@ -491,7 +491,7 @@
 	  (koi8-u) and Belarusian (koi8-ru) character sets.
 
 config NLS_UTF8
-	tristate "NLS UTF8"
+	tristate "NLS UTF-8"
 	depends on NLS
 	help
 	  If you want to display filenames with native language characters