PCI: tegra: Fix reporting GPIO error value

Error code is stored in rp->reset_gpio and not in err variable.

Link: https://lore.kernel.org/r/20200414102512.27506-1-pali@kernel.org


Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Acked-by: Rob Herring <robh@kernel.org>