Do not draw anything during DrawLogo.
Do not draw anything during DrawLogo.

Previously a series of diagonal color lines would be drawn to the
screen, and then quickly replaced by the boot logo.  Now the
screen will remain black until the boot logo is shown.

git-svn-id: 5648d1bec6962b0a6d1d1b40eba8cf5cdb62da3d@8689 6f19259b-4bc3-4df7-8a09-765794883524

MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2