ARM: uniphier: support system reset functionality for PSCI

This supports the system reset via PSCI for ARMv7 SoCs.

Because the system reset is not supported on PSCI 0.1, let's define
CONFIG_ARMV7_PSCI_1_0. (it is supported since PSCI 0.2, but there
is no CONFIG to enable it in U-Boot for now.)

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>