Factor out the the code to calculate the correct DPD register and bit
number for a given pad. This logic will be needed to query the status
register.
Signed-off-by: Aapo Vienamo <avienamo@nvidia.com>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>