ArmPkg/ArmScmiDxe: Add clock enable function

Add function to allow enabling and disabling of the clock using the SCMI
interface. Add gArmScmiClock2ProtocolGuid to distinguish platforms that
support new API from those that just have the older protocol.

SCMI_CLOCK2_PROTOCOL also adds a version parameter to allow for future
changes. It is placed after the functions that are present in the
existing protocol to allow SCMI_CLOCK2_PROTOCOL to be cast to
SCMI_CLOCK_PROTOCOL so that only a single implementation of those
function are needed.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jeff Brasen <jbrasen@nvidia.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>