hwrng: starfive - Fix dev_err_probe return error

Current dev_err_probe will return 0 instead of proper error code if
driver failed to get irq number. Fix the return err code.

Signed-off-by: Jia Jie Ho <jiajie.ho@starfivetech.com>
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <error27@gmail.com>
Closes: https://lore.kernel.org/r/202311160649.3GhKCfhd-lkp@intel.com/


Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>