gpiolib: acpi: make acpi_can_fallback_to_crs() static

It is not used outside gpiolib-acpi.c module, so there is no need to
export it.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Link: https://lore.kernel.org/r/20190904172624.GA76617@dtor-ws


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