UPSTREAM: clk: rockchip: mark pclk_ddrupctl as critical_clock on rk3036

UPSTREAM: clk: rockchip: mark pclk_ddrupctl as critical_clock on rk3036

No driver to handle this clk yet, but chip design requiress for this clock
supplying the ddr controller to be always on.

Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
(cherry picked from git.kernel.org mmind/linux-rockchip.git v4.13-clk/next
 commit f2893aaba435fcb55b86dc1be8c6f64f8d60e64b)

Change-Id: I3cd9578f73a69eb0f09d1f40c22ee55b393149aa
Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>