Hello,
I implementated the aura component with flattening Custom metadata. Please refer the following code which worked for me.
Aura Component:

<aura:component implements="flexipage:availableForAllPageTypes" Controller="GetCustomMetadata">

     <!-- This attribute saves the record ID -->
     <aura:attribute name="mydata" type="Object"/>
     <aura:attribute name="mycolumns" type="List"/>
     <aura:attribute name="recordLoadError" type="String"/>
     <aura:handler name="init" value="{!this}" action="{!c.doInit}"/>

     <lightning:datatable data="{! v.mydata }" 
        columns="{! v.mycolumns }" 
        keyField="Id"/>

</aura:component>

JS Function:

doInit : function(component, event, helper) {
        var action = component.get('c.getServiceProviders');
        component.set('v.mycolumns', [
            {label: 'Object Name', fieldName: 'ObjectName', type: 'text'},
            {label: 'Master Label', fieldName: 'MasterLabel', type: 'text'}
        ]);
        action.setCallback(this, $A.getCallback(function (response) {
            var state = response.getState();
            if (state === "SUCCESS") {
                var rows = response.getReturnValue();
                for(var i = 0 ; i < rows.length;i++) {
                    var row = rows[i];
                    row.ObjectName = row.Object_Type__r.DeveloperName;
                }
                component.set('v.mydata', rows);
            } else if (state === "ERROR") {
                var errors = response.getError();
            }
        }));
        $A.enqueueAction(action);
    }

Apex Controller:

public with sharing class GetCustomMetadata {
    @AuraEnabled
    public static List<Service_Provider__mdt> getServiceProviders(){
        return [
            SELECT
                MasterLabel,
                Object_Type__r.DeveloperName
            FROM
                Service_Provider__mdt
        ];
    }
}

Hope this helps you
If this helps kindly mark it as solved so that it may help others in future.

Thanks and Regards