gpio: grgpio: use a helper variable to store the address of ofdev->dev

[ Upstream commit d036ae41cebdfae92666024163c109b8fef516fa ]

Instead of dereferencing the platform device pointer repeatedly, just
store its address in a helper variable.

Link: https://lore.kernel.org/r/20241015131832.44678-3-brgl@bgdev.pl


Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Stable-dep-of: 050b23d081da ("gpio: grgpio: Add NULL check in grgpio_probe")
Signed-off-by: Sasha Levin <sashal@kernel.org>