include: Add defines for SBI debug console extension

We add SBI debug console extension related defines to the
SBI ecall interface header.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Xiang W <wxjstz@126.com>