PCI: tegra194: Fix Root Port interrupt handling

PCI: tegra194: Fix Root Port interrupt handling

As part of Root Port interrupt handling, level-0 register is read first and
based on the bits set in that, corresponding level-1 registers are read for
further interrupt processing. Since both these values are currently read
into the same 'val' variable, checking level-0 bits the second time around
is happening on the 'val' variable value of level-1 register contents
instead of freshly reading the level-0 value again.

Fix by using different variables to store level-0 and level-1 registers
contents.

Link: https://lore.kernel.org/r/20220721142052.25971-11-vidyas@nvidia.com
Fixes: 5e6510231597 ("PCI: tegra: Add Tegra194 PCIe support")
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>