[CRYPTO] digest: Remove old HMAC implementation

This patch removes the old HMAC implementation now that nobody uses it
anymore.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/crypto/Kconfig b/crypto/Kconfig
index f07d923..1e2f39c 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -33,7 +33,7 @@
 	  cbc(aes).
 
 config CRYPTO_HMAC
-	bool "HMAC support"
+	tristate "HMAC support"
 	select CRYPTO_HASH
 	help
 	  HMAC: Keyed-Hashing for Message Authentication (RFC2104).