imx8m-ddrc: Set AHB and MAIN_AXI clocks together with DRAM freq
A small hack that mimics what NXP kernels do when going into low power modes. It appears to save about 60mW when idle.
I've been running it for a while on my phones with no apparent issues. Doesn't seem upstreamable at all, but maybe it's small enough to carry downstream until we get more devfreqs upstream?