handle Mali450 pmu correctly
Created by: mmind
Rockchip Utgard Malis generally don't implement the PMU block, so it looks like I forgot to adapt the power-up sequence for the recent Mali450 support.
As can be seen in the diff, the handling is slightly different, was put together by looking at the GPL'ed mali/common/mali_pm.c and is obviously compile-tested only as my rk3328 always has everything turned on.