spi->irq was ignoring GpioInt property setting it to -1.
acpi_dev_gpio_irq_get returns and configure the slave IRQ according to
the ACPI slave node description.

It is now inline with devicetree behavior.
Acked-by: NMark Brown <broonie@kernel.org>
Signed-off-by: NChristophe Ricard <christophe-h.ricard@st.com>
Acked-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>