The GPU GX GDSC has GPU_GX_BCR reset and gfx3d_clk CXC, as stated
on downstream kernels (and as verified upstream, because otherwise
random lockups happen).
Also, add PWRSTS_RET and NO_RET_PERIPH: also as found downstream,
and also as verified here, to avoid GPU related lockups it is
necessary to force retain mem, but *not* peripheral when enabling
this GDSC (and, of course, the inverse on disablement).

With this change, the GPU finally works flawlessly on my four
different MSM8998 devices from two different manufacturers.
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Link: https://lore.kernel.org/r/20210114221059.483390-11-angelogioacchino.delregno@somainline.orgSigned-off-by: Stephen Boyd <sboyd@kernel.org>