media: staging: tegra-vde: Runtime PM is always available on Tegra

Runtime PM is always available on Tegra nowadays since commit 40b2bb1b
("ARM: tegra: enforce PM requirement"), hence the case of unavailable RPM
doesn't need to be handled.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>