Fix misspellings of "whether" in comments.

"Whether" is misspelled in various comments across the tree; 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/include/linux/lru_cache.h b/include/linux/lru_cache.h
index 7a71ffa..cafc7f9 100644
--- a/include/linux/lru_cache.h
+++ b/include/linux/lru_cache.h
@@ -52,8 +52,8 @@
 
 For crash recovery after replication node failure,
   we need to resync all regions that have been target of in-flight WRITE IO
-  (in use, or "hot", regions), as we don't know wether or not those WRITEs have
-  made it to stable storage.
+  (in use, or "hot", regions), as we don't know whether or not those WRITEs
+  have made it to stable storage.
 
   To avoid a "full resync", we need to persistently track these regions.