ata: ahci: use hweight_long() to count port_map bits

Replace the open loop used to calculate the number of set bits
in the port mapping with the `hweight_long()` function, which
simplifies the code without altering its functionality.

Signed-off-by: TanZheng <tanzheng@kylinos.cn>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Signed-off-by: Niklas Cassel <cassel@kernel.org>

Author: TanZheng

drivers/ata/libahci.c

@@ -552,11 +552,7 @@ void ahci_save_initial_config(struct device *dev, struct ahci_host_priv *hpriv)
 
 	/* cross check port_map and cap.n_ports */
 	if (port_map) {
-		int map_ports = 0;
-
-		for (i = 0; i < AHCI_MAX_PORTS; i++)
-			if (port_map & (1 << i))
-				map_ports++;
+		int map_ports = hweight_long(port_map);
 
 		/* If PI has more ports than n_ports, whine, clear
 		 * port_map and let it be generated from n_ports.