thermal: tegra: Nuke clk_{readl,writel} helpers

Naming driver-specific register accessors with generic
names, such as clk_writel and clk_readl, is bad.

Moreover, clk_writel and clk_readl are part of the
common clock framework api, so readers and code
grep'ers get confused by this collision.

The helpers are used once, so just remove them.

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>