ACPI / gpio: Add irq_type when a GPIO is used as an interrupt

When a GPIO is used as an interrupt in ACPI, the irq_type was not
available for device driver.

Make available polarity and triggering information in acpi_find_gpio by
renaming acpi_gpio_info field active_low  to polarity and adding triggering
field (edge/level).

For sanity, in gpiolib.c replace info.active_low by
"info.polarity == GPIO_ACTIVE_LOW".

Set the irq_type if necessary in acpi_dev_gpio_irq_get.

Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>