Revert "page_alloc.c: min_free_kbytes = 4096"

This reverts commit c440b1b7b32b42ec365190c36d5da74471dfda3d.
Revert "Revert "page_alloc.c: min_free_kbytes = 4096""

This reverts commit dc3411cd9c5cbdd5ff84901e0ec74fe1f51d99bb.
Enable zcache -
Now we have a stable config and sorted out the reason for sound crashes. The virtual clocks for iva and dsp were causing a system crash and alsa routing to be failed. Now we have to figure how zcache and uksm will work together.