When TerminalDxe Start() is called multiple times, the old logic
unconditionally appended the terminal device path candidates to
*Dev (ConInDev/ConOutDev/ErrOutDev), resulting the volatile storage
is full.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>