firmware: qcom: scm: Simplify with of_machine_device_match()

Replace open-coded getting root OF node and matching against it with
new of_machine_device_match() helper.

Reviewed-by: Konrad Dybcio <[e-mail]>
Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Reviewed-by: AngeloGioacchino Del Regno <[e-mail]>
Tested-by: AngeloGioacchino Del Regno <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Rob Herring (Arm) <[e-mail]>

drivers/firmware/qcom/qcom_scm.c

···
 	{ }
 };
 
-static bool qcom_scm_qseecom_machine_is_allowed(void)
-{
-	struct device_node *np;
-	bool match;
-
-	np = of_find_node_by_path("/");
-	if (!np)
-		return false;
-
-	match = of_match_node(qcom_scm_qseecom_allowlist, np);
-	of_node_put(np);
-
-	return match;
-}
-
 static void qcom_scm_qseecom_free(void *data)
 {
 	struct platform_device *qseecom_dev = data;
···
 
 	dev_info(scm->dev, "qseecom: found qseecom with version 0x%x\n", version);
 
-	if (!qcom_scm_qseecom_machine_is_allowed()) {
+	if (!of_machine_device_match(qcom_scm_qseecom_allowlist)) {
 		dev_info(scm->dev, "qseecom: untested machine, skipping\n");
 		return 0;
 	}