crypto: sha - split sha.h into sha1.h and sha2.h

Currently <crypto/sha.h> contains declarations for both SHA-1 and SHA-2,
and <crypto/sha3.h> contains declarations for SHA-3.

This organization is inconsistent, but more importantly SHA-1 is no
longer considered to be cryptographically secure.  So to the extent
possible, SHA-1 shouldn't be grouped together with any of the other SHA
versions, and usage of it should be phased out.

Therefore, split <crypto/sha.h> into two headers <crypto/sha1.h> and
<crypto/sha2.h>, and make everyone explicitly specify whether they want
the declarations for SHA-1, SHA-2, or both.

This avoids making the SHA-1 declarations visible to files that don't
want anything to do with SHA-1.  It also prepares for potentially moving
sha1.h into a new insecure/ or dangerous/ directory.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/sha1_generic.c b/crypto/sha1_generic.c
index 1d43472..325b57f 100644
--- a/crypto/sha1_generic.c
+++ b/crypto/sha1_generic.c
@@ -16,7 +16,7 @@
 #include <linux/module.h>
 #include <linux/mm.h>
 #include <linux/types.h>
-#include <crypto/sha.h>
+#include <crypto/sha1.h>
 #include <crypto/sha1_base.h>
 #include <asm/byteorder.h>