The existing SBI specification impelementation follows v0.1
specification. The latest specification allows more scalability
and performance improvements.

Rename the existing implementation as v0.1 and provide a way
to allow future extensions.
Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>