Remove validation on GCF regions (#3530)

* adding additional GCF regions supported 

Fixes https://github.com/terraform-providers/terraform-provider-google/issues/3515 
https://cloud.google.com/functions/docs/locations

* remove region validation from google cloud functions

* remove for region check resource creation

google/resource_cloudfunctions_function.go

@@ -27,10 +27,6 @@ var functionAllowedMemory = map[int]bool{
 	2048: true,
 }
 
-// For now CloudFunctions are allowed only in the following locations.
-// Please see https://cloud.google.com/about/locations/
-var validCloudFunctionRegion = validation.StringInSlice([]string{"us-central1", "us-east1", "europe-west1", "asia-northeast1"}, true)
-
 const functionDefaultAllowedMemoryMb = 256
 
 type cloudFunctionId struct {
@@ -283,11 +279,10 @@ func resourceCloudFunctionsFunction() *schema.Resource {
 			},
 
 			"region": {
-				Type:         schema.TypeString,
-				Optional:     true,
-				Computed:     true,
-				ForceNew:     true,
-				ValidateFunc: validCloudFunctionRegion,
+				Type:     schema.TypeString,
+				Optional: true,
+				Computed: true,
+				ForceNew: true,
 			},
 		},
 	}
@@ -305,14 +300,6 @@ func resourceCloudFunctionsCreate(d *schema.ResourceData, meta interface{}) erro
 	if err != nil {
 		return err
 	}
-	// We do this extra validation here since most regions are not valid, and the
-	// error message that Cloud Functions has for "wrong region" is not specific.
-	// Provider-level region fetching skips validation, because it's not possible
-	// for the provider-level region to know about the field-level validator.
-	_, errs := validCloudFunctionRegion(region, "region")
-	if len(errs) > 0 {
-		return errs[0]
-	}
 
 	cloudFuncId := &cloudFunctionId{
 		Project: project,