gpio: eic-sprd: Clear interrupt after set the interrupt type

The raw interrupt status of eic maybe set before the interrupt is enabled,
since the eic interrupt has a latch function, which would trigger the
interrupt event once enabled it from user side. To solve this problem,
interrupts generated before setting the interrupt trigger type are ignored.

Fixes: 25518e02 ("gpio: Add Spreadtrum EIC driver support")
Acked-by: Chunyan Zhang <zhang.lyra@gmail.com>
Signed-off-by: Wenhua Lin <Wenhua.Lin@unisoc.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>