efi_selftest: creating new handle in controller test

When the last protocol interface is uninstalled the handle is deleted but
this does not set the value of the handle to NULL.

To create a new handle with OpenProtocolInterface the value of the handle
must be NULL.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>

lib/efi_selftest/efi_selftest_controllers.c

@@ -134,6 +134,8 @@ static efi_status_t EFIAPI start(
 
 	/* Create child controllers */
 	for (i = 0; i < NUMBER_OF_CHILD_CONTROLLERS; ++i) {
+		/* Creating a new handle for the child controller */
+		handle_child_controller[i] = 0;
 		ret = boottime->install_protocol_interface(
 			&handle_child_controller[i], &guid_child_controller,
 			EFI_NATIVE_INTERFACE, NULL);