clk: tegra: Fix type for m field

When used as part of fractional ndiv calculations, the current range is
not enough because the denominator of the fraction is multiplied with m.

Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
Tested-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>