crypto: marvell/octeontx - Use swap() instead of open coding it

Clean the following coccicheck warning:

./drivers/crypto/marvell/octeontx/otx_cptvf_algs.c:1645:16-17: WARNING
opportunity for swap().
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/marvell/octeontx/otx_cptvf_algs.c

@@ -1639,11 +1639,8 @@ static void swap_func(void *lptr, void *rptr, int size)
 {
 	struct cpt_device_desc *ldesc = (struct cpt_device_desc *) lptr;
 	struct cpt_device_desc *rdesc = (struct cpt_device_desc *) rptr;
-	struct cpt_device_desc desc;
 
-	desc = *ldesc;
-	*ldesc = *rdesc;
-	*rdesc = desc;
+	swap(*ldesc, *rdesc);
 }
 
 int otx_cpt_crypto_init(struct pci_dev *pdev, struct module *mod,