Older device-trees don't specify padctrl interrupt and xhci-tegra driver
now fails to probe with -EINVAL using those device-trees. Check interrupt
presence and keep runtime PM disabled if it's missing to fix the trouble.

Fixes: 971ee247 ("usb: xhci: tegra: Enable ELPG for runtime/system PM")
Cc: <stable@vger.kernel.org> # 5.14+
Reported-by: Nicolas Chauvet <kwizart@gmail.com>
Tested-by: Nicolas Chauvet <kwizart@gmail.com> # T124 TK1
Tested-by: Thomas Graichen <thomas.graichen@gmail.com> # T124 Nyan Big
Tested-by: Thierry Reding <treding@nvidia.com> # Tegra CI
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Link: https://lore.kernel.org/r/20211107224455.10359-1-digetx@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>