Revert "Revert "gpio: omap: Fix lost edge wake-up interrupts""

This reverts commit 579ced8f

.

Turns out I was overly optimistic about cpu_pm blocking idle being a
solution for handling edge interrupts. While it helps in preventing
entering idle states that potentially lose context, we can still get
an edge interrupt triggering while entering idle. So we need to also
add back the workaround for seeing if there are any pending edge
interrupts when waking up.

Signed-off-by: Tony Lindgren <tony@atomide.com>
Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: Keerthy <j-keerthy@ti.com>
Cc: Ladislav Michl <ladis@linux-mips.org>
Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Tero Kristo <t-kristo@ti.com>
Link: https://lore.kernel.org/r/20201028060556.56038-1-tony@atomide.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>