hclk_cpubus needs to keep running because it is needed for devices like
the rom, i2s0 or spdif to be accessible via cpu. Without that all
accesses to devices (readl/writel) return wrong data. So add it
to the list of critical clocks.

Fixes: 78eaf609 ("clk: rockchip: disable unused clocks")
Signed-off-by: Alexander Kochetkov <al.kochet@gmail.com>
Cc: stable@vger.kernel.org # 4.1.x-
Signed-off-by: Heiko Stuebner <heiko@sntech.de>