devm_kcalloc() can fail and return NULL so we need to check for that.

Cc: stable@vger.kernel.org
Fixes: 58472f5c ("tpm: validate TPM 2.0 commands")
Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>