Remove no longer needed port check

The communicator code base will default to the correct port settings for
valid communicators and fail the build for non valid communicators.

builder/amazon/common/run_config.go

@@ -427,13 +427,6 @@ func (c *RunConfig) Prepare(ctx *interpolate.Context) []error {
 	// Validation
 	errs := c.Comm.Prepare(ctx)
 
-	if port := c.Comm.Port(); port == 0 {
-		if c.Comm.Type != "none" {
-			err := fmt.Errorf("port must be set to a non-zero value for a communicator of type %s", c.Comm.Type)
-			errs = append(errs, err)
-		}
-	}
-
 	// Copy singular tag maps
 	errs = append(errs, c.RunTag.CopyOn(&c.RunTags)...)
 	errs = append(errs, c.SpotTag.CopyOn(&c.SpotTags)...)