clk: tegra: Export Tegra20 EMC kernel symbols

We're going to modularize Tegra EMC drivers and some of the EMC-clock
driver symbols need to be exported.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20201104164923.21238-2-digetx@gmail.com


Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>