usb: typec: tcpm: Use fwnode_get_child_node_count()

Since fwnode_get_child_node_count() was split from its device property
counterpart, we may utilise it in the driver and drop custom implementation.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Acked-by: Kyle Tso <kyletso@google.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20250310150835.3139322-5-andriy.shevchenko@linux.intel.com
Signed-off-by: Lee Jones <lee@kernel.org>

Author: andy-shev

drivers/usb/typec/tcpm/tcpm.c

@@ -7166,7 +7166,7 @@ static void tcpm_fw_get_timings(struct tcpm_port *port, struct fwnode_handle *fw
 
 static int tcpm_fw_get_caps(struct tcpm_port *port, struct fwnode_handle *fwnode)
 {
-	struct fwnode_handle *capabilities, *child, *caps = NULL;
+	struct fwnode_handle *capabilities, *caps = NULL;
 	unsigned int nr_src_pdo, nr_snk_pdo;
 	const char *opmode_str;
 	u32 *src_pdo, *snk_pdo;
@@ -7232,9 +7232,7 @@ static int tcpm_fw_get_caps(struct tcpm_port *port, struct fwnode_handle *fwnode
 	if (!capabilities) {
 		port->pd_count = 1;
 	} else {
-		fwnode_for_each_child_node(capabilities, child)
-			port->pd_count++;
-
+		port->pd_count = fwnode_get_child_node_count(capabilities);
 		if (!port->pd_count) {
 			ret = -ENODATA;
 			goto put_capabilities;