esp, ah: consolidate the crypto algorithm selections

Instead of duplicating the algorithm selections between INET_AH and
INET6_AH and between INET_ESP and INET6_ESP, create new tristates
XFRM_AH and XFRM_ESP that do the algorithm selections, and make these be
selected by the corresponding INET* options.

Suggested-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Corentin Labbe <clabbe@baylibre.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/ipv4/Kconfig

@@ -340,11 +340,7 @@ config NET_FOU_IP_TUNNELS
 
 config INET_AH
 	tristate "IP: AH transformation"
-	select XFRM_ALGO
-	select CRYPTO
-	select CRYPTO_HMAC
-	select CRYPTO_MD5
-	select CRYPTO_SHA1
+	select XFRM_AH
 	---help---
 	  Support for IPsec AH.
 
@@ -352,15 +348,7 @@ config INET_AH
 
 config INET_ESP
 	tristate "IP: ESP transformation"
-	select XFRM_ALGO
-	select CRYPTO
-	select CRYPTO_AUTHENC
-	select CRYPTO_HMAC
-	select CRYPTO_MD5
-	select CRYPTO_CBC
-	select CRYPTO_SHA1
-	select CRYPTO_DES
-	select CRYPTO_ECHAINIV
+	select XFRM_ESP
 	---help---
 	  Support for IPsec ESP.