Fix misspelling of "should" and "shouldn't" in comments.

Some comments misspell "should" or "shouldn't"; this fixes them. No code changes.

Signed-off-by: Adam Buchbinder <adam.buchbinder@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/input/tablet/aiptek.c b/drivers/input/tablet/aiptek.c
index 7d005a3..4be039d 100644
--- a/drivers/input/tablet/aiptek.c
+++ b/drivers/input/tablet/aiptek.c
@@ -362,7 +362,7 @@
 };
 
 /***********************************************************************
- * Map values to strings and back. Every map shoudl have the following
+ * Map values to strings and back. Every map should have the following
  * as its last element: { NULL, AIPTEK_INVALID_VALUE }.
  */
 #define AIPTEK_INVALID_VALUE	-1