scripts/spelling.txt: add "swith" pattern and fix typo instances

Fix typos and add the following to the scripts/spelling.txt:

  swith||switch
  swithable||switchable
  swithed||switched
  swithing||switching

While we are here, fix the "update" to "updates" in the touched hunk in
drivers/net/wireless/marvell/mwifiex/wmm.c.

Link: http://lkml.kernel.org/r/1481573103-11329-2-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
index c28b0af..6e7b6a0 100644
--- a/net/mac80211/mesh.c
+++ b/net/mac80211/mesh.c
@@ -681,7 +681,7 @@ ieee80211_mesh_build_beacon(struct ieee80211_if_mesh *ifmsh)
 		   2 + /* NULL SSID */
 		   /* Channel Switch Announcement */
 		   2 + sizeof(struct ieee80211_channel_sw_ie) +
-		   /* Mesh Channel Swith Parameters */
+		   /* Mesh Channel Switch Parameters */
 		   2 + sizeof(struct ieee80211_mesh_chansw_params_ie) +
 		   2 + 8 + /* supported rates */
 		   2 + 3; /* DS params */