platform/x86: barco-p50-gpio: convert to guard() notation

platform/x86: barco-p50-gpio: convert to guard() notation

Using guard notation simplifies control flow and makes the code clearer.

Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Link: https://patch.msgid.link/20260318-barco-p50-gpio-set-v2-2-c0a4a6416163@gmail.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>