sh: clkfwk: Use arch_clk_init() for on-chip clock registration.

CPUs registering on-chip clocks should be using arch_clk_init() with the
new scheme so that the CPUs have the opportunity to establish the
topology prior to the initial root clock rate propagation. This ensures
that CPUs with on-chip clocks that use CLK_ENABLE_ON_INIT are properly
enabled at the initial propagation time, without having to further poke
the root clocks.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>