clk: tegra: export clock names for debugging

clk: tegra: export clock names for debugging

When writing a module for testing or debugging purposes, there is no way to
get hold of clk handles. This patch solves this by exposing all valid clocks
as clkdev's for the virtual device tegra-clk-debug.

Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>