clk: tegra: Mark HCLK, SCLK and EMC as critical

Machine dies if HCLK, SCLK or EMC is disabled. Hence mark these clocks
as critical.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Cc: <stable@vger.kernel.org> # v4.16
Signed-off-by: Thierry Reding <treding@nvidia.com>