soc: fsl: cpm1: qmc: Introduce qmc_chan_count_phandles()

No function in the QMC API is available to get the number of phandles
present in a phandle list.

Fill this lack introducing qmc_chan_count_phandles().
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Link: https://patch.msgid.link/20240701113038.55144-9-herve.codina@bootlin.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/soc/fsl/qe/qmc.c

@@ -1777,6 +1777,19 @@ static struct qmc_chan *qmc_chan_get_from_qmc(struct device_node *qmc_np, unsign
 	return qmc_chan;
 }
 
+int qmc_chan_count_phandles(struct device_node *np, const char *phandles_name)
+{
+	int count;
+
+	/* phandles are fixed args phandles with one arg */
+	count = of_count_phandle_with_args(np, phandles_name, NULL);
+	if (count < 0)
+		return count;
+
+	return count / 2;
+}
+EXPORT_SYMBOL(qmc_chan_count_phandles);
+
 struct qmc_chan *qmc_chan_get_byphandles_index(struct device_node *np,
 					       const char *phandles_name,
 					       int index)

include/soc/fsl/qe/qmc.h

@@ -16,6 +16,8 @@ struct device_node;
 struct device;
 struct qmc_chan;
 
+int qmc_chan_count_phandles(struct device_node *np, const char *phandles_name);
+
 struct qmc_chan *qmc_chan_get_byphandles_index(struct device_node *np,
 					       const char *phandles_name,
 					       int index);