Add basic tegra30 clock framework. Not all clocks are supported yet. Mainly
clocks requiring voltage scaling are not yet implemented in this version.

Based on work by Alex Frid <afrid@nvidia.com> and
Scott Williams <scwilliams@nvidia.com>.
Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Tested-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Olof Johansson <olof@lixom.net>