Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/include/net/wpan-phy.h b/include/net/wpan-phy.h
index 8592623..d86fffd 100644
--- a/include/net/wpan-phy.h
+++ b/include/net/wpan-phy.h
@@ -28,7 +28,7 @@
 	struct mutex pib_lock;
 
 	/*
-	 * This is a PIB acording to 802.15.4-2006.
+	 * This is a PIB according to 802.15.4-2006.
 	 * We do not provide timing-related variables, as they
 	 * aren't used outside of driver
 	 */