MdeModulePkg/TerminalDxe: Set NullRemaining to FALSE by default

MdeModulePkg/TerminalDxe: Set NullRemaining to FALSE by default

This is bug fix for TerminalDxe: NullRemaining should be set to FALSE
by fault and then be set to TRUE conditionally.

Cc: Feng Tian <feng.tian@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Heyi Guo <heyi.guo@linaro.org>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18026 6f19259b-4bc3-4df7-8a09-765794883524