[IPSEC]: Add support for aes-ctr.

The below patch allows IPsec to use CTR mode with AES encryption
algorithm. Tested this using setkey in ipsec-tools.

Signed-off-by: Joy Latten <latten@austin.ibm.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/pfkeyv2.h b/include/linux/pfkeyv2.h
index 6db69ff..700725d 100644
--- a/include/linux/pfkeyv2.h
+++ b/include/linux/pfkeyv2.h
@@ -298,6 +298,7 @@
 #define SADB_X_EALG_BLOWFISHCBC		7
 #define SADB_EALG_NULL			11
 #define SADB_X_EALG_AESCBC		12
+#define SADB_X_EALG_AESCTR		13
 #define SADB_X_EALG_AES_CCM_ICV8	14
 #define SADB_X_EALG_AES_CCM_ICV12	15
 #define SADB_X_EALG_AES_CCM_ICV16	16