MdeModulePkg: Removed valid text mode check in SetAttribute interface in GraphicsConsole.

MdeModulePkg: Removed valid text mode check in SetAttribute interface in GraphicsConsole.
UEFI spec mentioned that the color mask can be set even when the device is in an invalid text mode. But the current code add text mode check. Removed the check now.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Elvin Li <elvin.li@intel.com>
Reviewed-by: Jaben Carsey <Jaben.Carsey@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15721 6f19259b-4bc3-4df7-8a09-765794883524