CC3XX: Fix -Wmaybe-uninitialized build warning

Fix warning: 'cc_err' may be used uninitialized when
CC312_LEGACY_DRIVER_API_ENABLED is OFF.

Signed-off-by: Summer Qin <summer.qin@arm.com>
Change-Id: I8ea40468b4a1c264a0a90bc834cbb774a9e2acab
diff --git a/lib/ext/cryptocell-312-runtime/codesafe/src/psa_driver_api/src/cc3xx_psa_asymmetric_signature.c b/lib/ext/cryptocell-312-runtime/codesafe/src/psa_driver_api/src/cc3xx_psa_asymmetric_signature.c
index adfc0e0..ea718e7 100644
--- a/lib/ext/cryptocell-312-runtime/codesafe/src/psa_driver_api/src/cc3xx_psa_asymmetric_signature.c
+++ b/lib/ext/cryptocell-312-runtime/codesafe/src/psa_driver_api/src/cc3xx_psa_asymmetric_signature.c
@@ -76,7 +76,7 @@
     const CCEcpkiDomain_t *pDomain;
     CCEcpkiBuildTempData_t temp_data;
     psa_status_t err = PSA_ERROR_CORRUPTION_DETECTED;
-    CCError_t cc_err;
+    CCError_t cc_err = CC_FAIL;
 
     err = cc3xx_psa_hash_mode_to_cc_hash_mode(alg, do_hashing, &hash_mode);
     if (err != PSA_SUCCESS) {