crypto: omap-aes - Remove VLA usage of skcipher

In the quest to remove all stack VLA usage from the kernel[1], this
replaces struct crypto_skcipher and SKCIPHER_REQUEST_ON_STACK() usage
with struct crypto_sync_skcipher and SYNC_SKCIPHER_REQUEST_ON_STACK(),
which uses a fixed stack size.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/drivers/crypto/omap-aes.h b/drivers/crypto/omap-aes.h
index fc3b46a..7e02920e 100644
--- a/drivers/crypto/omap-aes.h
+++ b/drivers/crypto/omap-aes.h
@@ -101,7 +101,7 @@ struct omap_aes_ctx {
 	int		keylen;
 	u32		key[AES_KEYSIZE_256 / sizeof(u32)];
 	u8		nonce[4];
-	struct crypto_skcipher	*fallback;
+	struct crypto_sync_skcipher	*fallback;
 	struct crypto_skcipher	*ctr;
 };