clk: Initialize struct clk_core kref earlier

Initialize this kref once we allocate memory for the struct clk_core so
that we can reuse the release function to free any memory associated
with the structure. This mostly consolidates code, but also clarifies
that the kref lifetime exists once the container structure (struct
clk_core) is allocated instead of leaving it in a half-baked state for
most of __clk_core_init().

Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/20240325184204.745706-4-sboyd@kernel.org