gpio: eic: sprd: Fix incorrect irq type setting for the sync EIC

commit 102bbe34b31c9159e714432afd64458f6f3876d7 upstream.

When setting sync EIC as IRQ_TYPE_EDGE_BOTH type, we missed to set the
SPRD_EIC_SYNC_INTMODE register to 0, which means detecting edge signals.

Thus this patch fixes the issue.

Fixes: 25518e02 ("gpio: Add Spreadtrum EIC driver support")
Cc: <stable@vger.kernel.org>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>