dt-bindings: Fix entry name for I/O High Voltage property

Correct the name of the I/O High Voltage Property from
'nvidia,io-high-voltage' to 'nvidia,io-hv'.

Fixes: 2585a584 ("pinctrl: Add Tegra194 pinctrl DT bindings")
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>