arm64: dts: exynos: gs101: align poweroff writes with downstream

arm64: dts: exynos: gs101: align poweroff writes with downstream

For power off, downstream only clears bit 8 and leaves all other bits
untouched, whereas this here ends up setting bit 8 and clearing all
others, due to how sysconf-poweroff parses the DT.

I noticed this discrepancy while debugging some reboot related
differences between up- and downstream and it's useful to align the
behaviour here.

Note: for reboot downstream seems to be incorrectly writing 0x00000002
and not just setting bit 1 (which is the only R/W bit in this
register), so we keep that one as-is here.

Signed-off-by: André Draszik <andre.draszik@linaro.org>
Link: https://lore.kernel.org/r/20250210-gs101-renppt-dts-v2-2-fb33fda6fc4b@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>