crypto: export arc4 defines

Some arc4 cipher algorithm defines show up in two places:
crypto/arc4.c and drivers/crypto/bcm/cipher.h.
Let's export them in a common header and update their users.

Signed-off-by: Iuliana Prodan <iuliana.prodan@nxp.com>
Reviewed-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/arc4.c

@@ -13,14 +13,11 @@
  */
 
 #include <crypto/algapi.h>
+#include <crypto/arc4.h>
 #include <crypto/internal/skcipher.h>
 #include <linux/init.h>
 #include <linux/module.h>
 
-#define ARC4_MIN_KEY_SIZE	1
-#define ARC4_MAX_KEY_SIZE	256
-#define ARC4_BLOCK_SIZE		1
-
 struct arc4_ctx {
 	u32 S[256];
 	u32 x, y;