crypto: ixp4xx - silence uninitialized variable warning

Smatch complains that "dma" is uninitialized if dma_pool_alloc() fails.
This is true, but also harmless.  Anyway, move the assignment after the
error checking to silence this warning.

Fixes: 586d492f ("crypto: ixp4xx - fix building wiht 64-bit dma_addr_t")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/intel/ixp4xx/ixp4xx_crypto.c

@@ -1175,9 +1175,9 @@ static int aead_perform(struct aead_request *req, int encrypt,
 		/* The 12 hmac bytes are scattered,
 		 * we need to copy them into a safe buffer */
 		req_ctx->hmac_virt = dma_pool_alloc(buffer_pool, flags, &dma);
-		crypt->icv_rev_aes = dma;
 		if (unlikely(!req_ctx->hmac_virt))
 			goto free_buf_dst;
+		crypt->icv_rev_aes = dma;
 		if (!encrypt) {
 			scatterwalk_map_and_copy(req_ctx->hmac_virt,
 						 req->src, cryptlen, authsize, 0);