tests: dma: loop_transfer: add overlay for Nucleo-WB07CC

Add an overlay to the test so that proper DMA behavior can
be verified on STM32WB07 SoC.

Signed-off-by: Mathieu Choplain <[email protected]>

Author: mathieuchopstm

tests/drivers/dma/loop_transfer/boards/nucleo_wb07cc.conf

@@ -0,0 +1 @@
+CONFIG_DMA_LOOP_TRANSFER_CHANNEL_NR=7

tests/drivers/dma/loop_transfer/boards/nucleo_wb07cc.overlay

@@ -0,0 +1,12 @@
+/*
+ * Copyright (c) 2025 STMicroelectronics
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+&dma1 {
+	status = "okay";
+};
+
+tst_dma0: &dmamux1 {
+	status = "okay";
+};