ARM: configs: keystone: Enable TI-SCI protocol and genpd driver

Enable the TI-SCI core protocol and the corresponding genpd
driver to enable the essential infrastructure for various
device drivers on the 66AK2G family of SoCs. The TI-SCI Clock
driver is automatically enabled for ARCH_KEYSTONE.

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>