RiscVPlatformPkg/Sec: Initial hart_index2Id array

Initial hart index to Id array by invoking OpenSBI
fw_platform_init function.

Introduce PcdBootableHartIndexToId PCD which could be
used to overwrite the hart_index2Id arrary built
from Devie tree according to platform demand.

Cc: Sunil V L <sunilvl@ventanamicro.com>
Cc: Daniel Schaefer <daniel.schaefer@hpe.com>
Signed-off-by: Abner Chang <abner.chang@hpe.com>
Reviewed-by: Daniel Schaefer <daniel.schaefer@hpe.com>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>