arm64: dts: qcom: msm8992-bullhead: Remove PSCI

[ Upstream commit 9d1fc2e4 ]

Bullhead firmware obviously doesn't support PSCI as it fails to boot
with this definition.

Fixes: 329e16d5

 ("arm64: dts: qcom: msm8992: Add PSCI support.")
Signed-off-by: Petr Vorel <petr.vorel@gmail.com>
Link: https://lore.kernel.org/r/20210713185734.380-2-petr.vorel@gmail.com
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>