crypto: starfive - Remove unneeded NULL checks

NULL check before kfree_sensitive function is not needed.

Signed-off-by: Jia Jie Ho <jiajie.ho@starfivetech.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311301702.LxswfETY-lkp@intel.com/
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto: starfive - RSA poll csr for done status

Hardware could not clear irq status without resetting the entire module.
Driver receives irq immediately when mask bit is cleared causing
intermittent errors in RSA calculations. Switch to use csr polling for
done status instead.

Signed-off-by: Jia Jie Ho <jiajie.ho@starfivetech.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto: starfive - Add RSA algo support

Adding RSA enc/dec and sign/verify feature for StarFive cryptographic
module. The module only supports mod sizes up to 2048, therefore
calculations more than that will use fallback algo.

Co-developed-by: Huan Feng <huan.feng@starfivetech.com>
Signed-off-by: Huan Feng <huan.feng@starfivetech.com>
Signed-off-by: Jia Jie Ho <jiajie.ho@starfivetech.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>