gpio-langwell: drop away explicit casting

Since the type of the reg_base member is void __iomem * we don't need to have
explicit casting in gpio_reg() and gpio_reg_2bit().

Update year in the copyright notice as well.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: David Cohen <david.a.cohen@intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>