ARM: tegra: rename OUT_CLK_SOURCE_*

OUT_CLK_SOURCE_ are currently named after the number of bits the mask
they represent includes. However, bit count is not the only possible
variable; bit position may also vary. Rename OUT_CLK_SOURCE_ to
OUT_CLK_SOURCE_31_30_ and OUT_CLK_SOURCE4_ to OUT_CLK_SOURCE_31_28 to
more completely describe exactly what they represent, without having to
go look up the definitions.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Tested-by: Thierry Reding <treding@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>