gpio: mxc: remove dead code after switch to DT-only

struct platform_device::id was only set by board code, but since i.MX
became a devicetree-only platform, this will always be -1
(PLATFORM_DEVID_NONE).

Note: of_alias_get_id() returns a negative number on error and base
treats all negative errors the same, so we need not add any additional
error handling.

Fixes: 0f2c7af45d7e ("gpio: mxc: Convert the driver to DT-only")
Signed-off-by: Ahmad Fatoum <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Bartosz Golaszewski <[e-mail]>

drivers/gpio/gpio-mxc.c

···
 	port->gc.request = mxc_gpio_request;
 	port->gc.free = mxc_gpio_free;
 	port->gc.to_irq = mxc_gpio_to_irq;
-	port->gc.base = (pdev->id < 0) ? of_alias_get_id(np, "gpio") * 32 :
-					     pdev->id * 32;
+	port->gc.base = of_alias_get_id(np, "gpio") * 32;
 
 	err = devm_gpiochip_add_data(&pdev->dev, &port->gc, port);
 	if (err)