Now that the ahb clock on sun5i/sun7i is muxable, ahb is no longer
guaranteed to be a child of the cpu clock. Add the cpu clock to
the list of protected clocks so it doesn't get disabled.
Signed-off-by: NChen-Yu Tsai <wens@csie.org>
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>