gpio: stmpe: Remove unused 'dev' member of struct stmpe_gpio

There is no evidence that the 'dev' member of struct stmpe_gpio
is used, drop it.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240902133148.2569486-3-andriy.shevchenko@linux.intel.com


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