rockchip: clk: rk3368: remove unused fields from rk3368_clk_priv

The rk3368_clk_priv has two unused fields: rate, has_bwadj. This
removes them as there's no need for either (i.e. has_bwadj is always
true for the RK3368, according to its TRM).

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>