gpio: stmpe: Utilise temporary variable for struct device

We have a temporary variable to keep a pointer to struct device.
Utilise it where it makes sense.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240902133148.2569486-4-andriy.shevchenko@linux.intel.com


Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>