pinctrl: samsung: Do not pass gpio_chip to pin_to_reg_bank

The pointer to gpio_chip passed to pin_to_reg_bank utility function is
used only to retrieve a pointer to samsung_pinctrl_drv_data structure.

This patch modifies the function and its users to pass a pointer to
samsung_pinctrl_drv_data directly.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Thomas Abraham <thomas.abraham@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>