add CEL for DRPolicy immutability

Signed-off-by: rakeshgm <[email protected]>
(cherry picked from commit 3033b77d3646fa0ccffc2a21bba35b1071fa34bc)

api/v1alpha1/drpolicy_types.go

@@ -8,6 +8,7 @@ import (
 )
 
 // DRPolicySpec defines the desired state of DRPolicy
+// +kubebuilder:validation:XValidation:rule="self == oldSelf", message="Value is immutable"
 type DRPolicySpec struct {
 	// Important: Run "make" to regenerate code after modifying this file