mailbox: imx: populate sub-nodes

Some MUs such as i.MX95 MU, have internal SRAM which could be used
for SCMI shared memory, so populate the sub-nodes to use the SRAM.
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>

drivers/mailbox/imx-mailbox.c

@@ -16,6 +16,7 @@
 #include <linux/mailbox_controller.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/suspend.h>
@@ -920,6 +921,8 @@ static int imx_mu_probe(struct platform_device *pdev)
 	if (ret)
 		goto disable_clk;
 
+	of_platform_populate(dev->of_node, NULL, NULL, dev);
+
 	pm_runtime_enable(dev);
 
 	ret = pm_runtime_resume_and_get(dev);