clk: Use 'parent' to shorten lines in __clk_core_init()

Some lines are getting long in this function. Let's move 'parent' up to
the top of the function and use it in many places whenever there is a
parent for a clk. This shortens some lines by avoiding core->parent->
indirections.

Cc: Douglas Anderson <dianders@chromium.org>
Cc: Heiko Stuebner <heiko@sntech.de>
Cc: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lkml.kernel.org/r/20200205232802.29184-3-sboyd@kernel.org


Acked-by: Jerome Brunet <jbrunet@baylibre.com>