arm64: dts: hisilicon: poplar: Correct PCIe reset GPIO polarity

arm64: dts: hisilicon: poplar: Correct PCIe reset GPIO polarity

The PCIe reset GPIO on Poplar is actually active low.  The active high
worked before because kernel driver didn't respect the setting from DT.
This is changed since commit 1d26a55fbeb9 ("PCI: histb: Switch to using
gpiod API"), and thus PCIe on Poplar got brken since then.

Fix the problem by correcting the polarity.

Fixes: 32fa01761bd9 ("arm64: dts: hi3798cv200: enable PCIe support for poplar board")
Cc: stable@vger.kernel.org
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>