Revert "pldm: use std::expected for instance ID allocation"

This reverts commit 70262ed7bf854b25d4b65628bc3c892ddfe9380f.

Change-Id: I1f54d6b60bf3cfa9f00764140eec6167e1e182d6
Signed-off-by: Manojkiran Eda <manojkiran.eda@gmail.com>
diff --git a/libpldmresponder/platform.cpp b/libpldmresponder/platform.cpp
index 601964b..7a3b63c 100644
--- a/libpldmresponder/platform.cpp
+++ b/libpldmresponder/platform.cpp
@@ -980,12 +980,7 @@
     std::vector<uint8_t> requestMsg(
         sizeof(pldm_msg_hdr) + PLDM_SET_EVENT_RECEIVER_REQ_BYTES);
     auto request = new (requestMsg.data()) pldm_msg;
-    auto instanceIdResult = pldm::utils::getInstanceId(instanceIdDb->next(eid));
-    if (!instanceIdResult)
-    {
-        return;
-    }
-    auto instanceId = instanceIdResult.value();
+    auto instanceId = instanceIdDb->next(eid);
     uint8_t eventMessageGlobalEnable =
         PLDM_EVENT_MESSAGE_GLOBAL_ENABLE_ASYNC_KEEP_ALIVE;
     uint8_t transportProtocolType = PLDM_TRANSPORT_PROTOCOL_TYPE_MCTP;