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>