arm64: dts: qcom: sa8775p: pmic: remove the PON modes

On this PMIC, the PON peripheral does not provide passing reboot modes
over HLOS. They must be passed over SDAM. Remove the reboot-mode
properties as we'll provide a proper SDAM node in a later commit.

Fixes: d2d9a592 ("arm64: dts: qcom: sa8775p: add the Power On device node")
Signed-off-by: Parikshit Pareek <quic_ppareek@quicinc.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230417145536.414490-2-brgl@bgdev.pl