clk: support hardware-specific debugfs entries

Add a new clk_ops->debug_init method to allow a clock hardware
driver to populate the clock's debugfs directory with entries
beyond those common for every clock.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

diff --cc drivers/clk/clk.c
Simple merge

diff --cc include/linux/clk-provider.h
Simple merge