clk: tegra: Fix a bunch of sparse warnings

The second to last parameter of the TEGRA_CLK_PERIPH macro denotes a
table and should therefore users should pass in NULL instead of 0.

Fixes a bunch of sparse warnings like this:

	warning: Using plain integer as NULL pointer

Reviewed-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>