MdeModulePkg: Fix GraphicsConsole driver resolution out of sync issue

MdeModulePkg: Fix GraphicsConsole driver resolution out of sync issue

When the GOP doesn't support the resolution specified by
PcdVideoHorizontalResolution and PcdVideoVerticalResolution,
the code tries to set the resolution to 800x600 but uses the resolution
equals to the PCD when calculating the text print position.
The patch fixes the bug by updating the resolution to 800x600 for
this case.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19630 6f19259b-4bc3-4df7-8a09-765794883524