PCI: tegra194: Disable interrupts before entering L2

PCI: tegra194: Disable interrupts before entering L2

In suspend_noirq() call if link doesn't goto L2, PERST# is asserted
to bring link to detect state. However, this is causing surprise
link down AER error. Since Kernel is executing noirq suspend calls,
AER interrupt is not processed. PME and AER are shared interrupts
and PCIe subsystem driver enables wake capability of PME irq during
suspend. So this AER will cause suspend failure due to pending
AER interrupt.

After PCIe link is in L2, interrupts are not expected since PCIe
controller will be in reset state. Disable PCIe interrupts before
going to L2 state to avoid pending AER interrupt.

Link: https://lore.kernel.org/r/20210623100525.19944-4-omp@nvidia.com
Signed-off-by: Om Prakash Singh <omp@nvidia.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Vidya Sagar <vidyas@nvidia.com>