memory: tegra: read values from correct device

When reading MR18 for Dev1 the code was incorrectly reading the
value corresponding to Dev0, so fix this by adjusting the index
according to the Tegra X1 TRM.

Signed-off-by: Diogo Ivo <diogo.ivo@tecnico.ulisboa.pt>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20230322234050.47332-1-diogo.ivo@tecnico.ulisboa.pt


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>