Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 4b13d5d..afcc709 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -1113,7 +1113,7 @@
 	/*
 	 *	ipngwg API draft makes clear that the correct semantics
 	 *	for TCP and UDP is to consider one TCP and UDP instance
-	 *	in a host availiable by both INET and INET6 APIs and
+	 *	in a host available by both INET and INET6 APIs and
 	 *	able to communicate via both network protocols.
 	 */