arm: dts: e850-96: Remove not needed bootph-all flags

Most of the nodes in e850-96 appended device tree that add bootph-all
flags are not necessary. All those nodes are instantiated as
dependencies of other nodes anyway. Remove those nodes to avoid
cluttering the appended dts. 'bdinfo' reports 768 bytes reduction for
"Early malloc usage", and 'dm tree' output doesn't change. Keep only
pmu_system_controller changes, which are actually needed for serial to
work properly.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>