serial: 8250_pnp: Simplify "line" related code

8250_pnp sets drvdata to line + 1 if the probe is successful. The users
of drvdata are in remove, suspend and resume callbacks, none of which
will be called if probe failed. The line acquired from drvdata can
never be zero in those functions and the checks for that can be
removed.

Eliminate also +/-1 step because all users of line subtract 1 from the
value.

These might have been leftover from legacy PM callbacks that could
be called without probe being successful.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20240506121202.11253-1-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_pnp.c

@@ -435,8 +435,9 @@ static int
 serial_pnp_probe(struct pnp_dev *dev, const struct pnp_device_id *dev_id)
 {
 	struct uart_8250_port uart, *port;
-	int ret, line, flags = dev_id->driver_data;
+	int ret, flags = dev_id->driver_data;
 	unsigned char iotype;
+	long line;
 
 	if (flags & UNKNOWN_DEV) {
 		ret = serial_pnp_guess_board(dev);
@@ -494,7 +495,7 @@ serial_pnp_probe(struct pnp_dev *dev, const struct pnp_device_id *dev_id)
 	if (uart_console(&port->port))
 		dev->capabilities |= PNP_CONSOLE;
 
-	pnp_set_drvdata(dev, (void *)((long)line + 1));
+	pnp_set_drvdata(dev, (void *)line);
 	return 0;
 }
 
@@ -503,27 +504,22 @@ static void serial_pnp_remove(struct pnp_dev *dev)
 	long line = (long)pnp_get_drvdata(dev);
 
 	dev->capabilities &= ~PNP_CONSOLE;
-	if (line)
-		serial8250_unregister_port(line - 1);
+	serial8250_unregister_port(line);
 }
 
 static int serial_pnp_suspend(struct device *dev)
 {
 	long line = (long)dev_get_drvdata(dev);
 
-	if (!line)
-		return -ENODEV;
-	serial8250_suspend_port(line - 1);
+	serial8250_suspend_port(line);
 	return 0;
 }
 
 static int serial_pnp_resume(struct device *dev)
 {
 	long line = (long)dev_get_drvdata(dev);
 
-	if (!line)
-		return -ENODEV;
-	serial8250_resume_port(line - 1);
+	serial8250_resume_port(line);
 	return 0;
 }