clk: zx296718: do not panic on failure

Instead of using panic, we should give an error message and return error
code when of_clk_add_hw_provider() call fails.

Since we have error prompt for failures, the "init over" pr_info output
isn't really necessary but becomes a debug noise.  So let's clean it up
along the way.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>