crypto: qat - remove double initialization of value

Remove double initialization of the reg variable.

This is to fix the following warning when compiling the QAT driver
using clang scan-build:
    drivers/crypto/intel/qat/qat_common/adf_gen4_ras.c:1010:6: warning: Value stored to 'reg' during its initialization is never read [deadcode.DeadStores]
     1010 |         u32 reg = ADF_CSR_RD(csr, ADF_GEN4_SSMCPPERR);
          |             ^~~   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    drivers/crypto/intel/qat/qat_common/adf_gen4_ras.c:1109:6: warning: Value stored to 'reg' during its initialization is never read [deadcode.DeadStores]
     1109 |         u32 reg = ADF_CSR_RD(csr, ADF_GEN4_SER_ERR_SSMSH);
          |             ^~~   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fixes: 99b1c982 ("crypto: qat - count QAT GEN4 errors")
Signed-off-by: Adam Guerin <adam.guerin@intel.com>
Reviewed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>