treewide: Fix typos in various parts of the kernel, and fix some comments.

The below patch fixes some typos in various parts of the kernel, as well as fixes some comments.
Please let me know if I missed anything, and I will try to get it changed and resent.

Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 72eddd1..bd3487d 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1423,7 +1423,7 @@
  * DOC: Beacon filter support
  *
  * Some hardware have beacon filter support to reduce host cpu wakeups
- * which will reduce system power consumption. It usuallly works so that
+ * which will reduce system power consumption. It usually works so that
  * the firmware creates a checksum of the beacon but omits all constantly
  * changing elements (TSF, TIM etc). Whenever the checksum changes the
  * beacon is forwarded to the host, otherwise it will be just dropped. That