dm crypt: fix copy and paste bug in crypt_alloc_req_aead

In commit d68b29584c ("dm crypt: use GFP_ATOMIC when allocating
crypto requests from softirq") code was incorrectly copy and pasted
from crypt_alloc_req_skcipher()'s crypto request allocation code to
crypt_alloc_req_aead(). It is OK from runtime perspective as both
simple encryption request pointer and AEAD request pointer are part of
a union, but may confuse code reviewers.

Fixes: d68b29584c ("dm crypt: use GFP_ATOMIC when allocating crypto requests from softirq")
Cc: stable@vger.kernel.org # v5.9+
Reported-by: Pavel Machek <pavel@denx.de>
Signed-off-by: Ignat Korchagin <ignat@cloudflare.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-crypt.c

@@ -1481,9 +1481,9 @@ static int crypt_alloc_req_skcipher(struct crypt_config *cc,
 static int crypt_alloc_req_aead(struct crypt_config *cc,
 				 struct convert_context *ctx)
 {
-	if (!ctx->r.req) {
-		ctx->r.req = mempool_alloc(&cc->req_pool, in_interrupt() ? GFP_ATOMIC : GFP_NOIO);
-		if (!ctx->r.req)
+	if (!ctx->r.req_aead) {
+		ctx->r.req_aead = mempool_alloc(&cc->req_pool, in_interrupt() ? GFP_ATOMIC : GFP_NOIO);
+		if (!ctx->r.req_aead)
 			return -ENOMEM;
 	}