GenBiosId: Fixed a regression bug introduced by 8b72f720

8b72f720 introduced a regression bug that make GenBiosId
failed if -ot is passed to this tool.

This patch is going to fix it.

Signed-off-by: Bob Feng <bob.c.feng@intel.com>

Cc: Liming Gao <liming.gao@intel.com>
Cc: Kilian Kegel <kilian_kegel@outlook.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>