Fix typos in /Documentation : 'U-Z'

This patch fixes typos in various Documentation txts. The patch addresses some
+words starting with the letters 'U-Z'.

Looks like I made it through the alphabet...just in time to start over again
+too!  Maybe I can fit more profound fixes into the next round...?  Time will
+tell. :)

Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
diff --git a/Documentation/pnp.txt b/Documentation/pnp.txt
index 9ff966b..28037aa 100644
--- a/Documentation/pnp.txt
+++ b/Documentation/pnp.txt
@@ -184,7 +184,7 @@
 Please note that the character 'X' can be used as a wild card in the function
 portion (last four characters).
 ex:
-	/* Unkown PnP modems */
+	/* Unknown PnP modems */
 	{	"PNPCXXX",		UNKNOWN_DEV	},
 
 Supported PnP card IDs can optionally be defined.