Remove ASSERT when SetVariable for ConOutDev/ConInDev/ErrOutDev variables failed.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Elvin Li <elvin.li@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>


git-svn-id: svn://svn.code.sf.net/p/edk2/code/trunk/edk2/MdeModulePkg@15336 6f19259b-4bc3-4df7-8a09-765794883524