Revert "DPE: Use a 64-bit buffer in call to QCBOR API to retrieve cert_id"

This reverts commit 8512b5693bf70afa1c7fe715a650659b0c33d842.

Reason for revert: Negative DPE test fails: need to understand the root cause

Change-Id: I0559a924e566fb6fa47997cd01dc6ea3c8964287
Signed-off-by: Antonio de Angelis <antonio.deangelis@arm.com>
diff --git a/partitions/dice_protection_environment/dpe_cmd_decode.c b/partitions/dice_protection_environment/dpe_cmd_decode.c
index f941be8..fef4588 100644
--- a/partitions/dice_protection_environment/dpe_cmd_decode.c
+++ b/partitions/dice_protection_environment/dpe_cmd_decode.c
@@ -215,7 +215,6 @@
     uint8_t *new_certificate_buf = ALLOC_TEMP_BUF;
     uint8_t exported_cdi_buf[DICE_MAX_ENCODED_CDI_SIZE];
     uint32_t cert_id;
-    uint64_t cert_id64;
     size_t new_certificate_actual_size = 0;
     size_t exported_cdi_actual_size = 0;
     QCBORItem item;
@@ -253,7 +252,7 @@
     memcpy(&context_handle, out.ptr, out.len);
     COUNT_ARGS(num_of_valid_arguments);
 
-    QCBORDecode_GetUInt64InMapN(decode_ctx, DPE_DERIVE_CONTEXT_CERT_ID, &cert_id64);
+    QCBORDecode_GetUInt64InMapN(decode_ctx, DPE_DERIVE_CONTEXT_CERT_ID, &cert_id);
     /* Check if cert_id was encoded in the received command buffer */
     CHECK_AND_COUNT_OPTIONAL_ARGUMENT(decode_ctx);
 
@@ -314,13 +313,6 @@
         return DPE_INVALID_ARGUMENT;
     }
 
-    /* The QCBOR function uses a 64-bit pointer, but the context info is on 32 bit */
-    if (cert_id64 > UINT32_MAX) {
-        return DPE_INVALID_ARGUMENT;
-    }
-
-    cert_id = (uint32_t)cert_id64;
-
     dpe_err = derive_context_request(context_handle, cert_id, retain_parent_context,
                                      allow_new_context_to_derive, create_certificate,
                                      &dice_inputs, client_id,