tests/provider: Enable tfproviderlint R002 check (#12033)

Reference: #9952

Previously:

```
aws/resource_aws_sns_platform_application.go:230:18: R002: ResourceData.Set() pointer value dereference is extraneous
```

We are unable to acceptance test the `aws_sns_platform_application` resource as it requires an active Apple Developer subscription and application, however this final refactor is trivial.

GNUmakefile

@@ -69,6 +69,7 @@ lint:
 		-AT006 \
 		-AT007 \
 		-AT008 \
+		-R002 \
 		-R004 \
 		-R006 \
 		-R012 \

aws/resource_aws_sns_platform_application.go

@@ -225,9 +225,9 @@ func resourceAwsSnsPlatformApplicationRead(d *schema.ResourceData, meta interfac
 				// Some of the fetched attributes are stateful properties such as
 				// the number of subscriptions, the owner, etc. skip those
 				if resource.Schema[iKey] != nil {
-					value := *attrmap[oKey]
+					value := aws.StringValue(attrmap[oKey])
 					log.Printf("[DEBUG] Updating %s => %s -> %s", iKey, oKey, value)
-					d.Set(iKey, *attrmap[oKey])
+					d.Set(iKey, value)
 				}
 			}
 		}