crypto: chacha20 - Fix keystream alignment for chacha20_block()

When chacha20_block() outputs the keystream block, it uses 'u32' stores
directly.  However, the callers (crypto/chacha20_generic.c and
drivers/char/random.c) declare the keystream buffer as a 'u8' array,
which is not guaranteed to have the needed alignment.

Fix it by having both callers declare the keystream as a 'u32' array.
For now this is preferable to switching over to the unaligned access
macros because chacha20_block() is only being used in cases where we can
easily control the alignment (stack buffers).

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

lib/chacha20.c

@@ -21,7 +21,7 @@ static inline u32 rotl32(u32 v, u8 n)
 	return (v << n) | (v >> (sizeof(v) * 8 - n));
 }
 
-extern void chacha20_block(u32 *state, void *stream)
+void chacha20_block(u32 *state, u32 *stream)
 {
 	u32 x[16], *out = stream;
 	int i;