gpio: dwapb: Call acpi_gpiochip_free_interrupts() on GPIO chip de-registration

gpio: dwapb: Call acpi_gpiochip_free_interrupts() on GPIO chip de-registration

Add missed acpi_gpiochip_free_interrupts() call when unregistering ports.

While at it, drop extra check to call acpi_gpiochip_request_interrupts().
There is no need to have an additional check to call
acpi_gpiochip_request_interrupts(). Even without any interrupts available
the registered ACPI Event handlers can be useful for debugging purposes.

Fixes: e6cb3486f5a1 ("gpio: dwapb: add gpio-signaled acpi event support")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Serge Semin <fancer.lancer@gmail.com>
Acked-by: Serge Semin <fancer.lancer@gmail.com>
Link: https://lore.kernel.org/r/20200519131233.59032-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>