gpiolib: Preserve desc->flags when setting state

mainline inclusion
from mainline-v5.3-rc3
commit d95da993
category: bugfix
bugzilla: 14225
CVE: NA

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desc->flags may already have values set by of_gpiochip_add() so make
sure that this isn't undone when setting the initial direction.

Cc: stable@vger.kernel.org
Fixes: 3edfb7bd ("gpiolib: Show correct direction from the beginning")
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Link: https://lore.kernel.org/r/20190707203558.10993-1-chris.packham@alliedtelesis.co.nz


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>