gpio-lynxpoint: force gpio_get() to return "1" and "0" only

Don't return the IN_LVL_BIT directly, a high gpio line returned
value "1073741824" intestead of "1" because IN_LVL_BIT is BIT(30)

Tested-by: Jerome Blin <jerome.blin@intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>