lib: sbi: Fix domain_count check in sbi_domain_finalize()

The domain_count check in sbi_domain_finalize() for newly discovered
domain is incorrect and should be reversed.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>