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>

include/crypto/arc4.h

@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Common values for ARC4 Cipher Algorithm
+ */
+
+#ifndef _CRYPTO_ARC4_H
+#define _CRYPTO_ARC4_H
+
+#define ARC4_MIN_KEY_SIZE	1
+#define ARC4_MAX_KEY_SIZE	256
+#define ARC4_BLOCK_SIZE		1
+
+#endif /* _CRYPTO_ARC4_H */