CorebootModulePkg/CbSupportPei: Mask off all legacy 8259 interrupt sources

CorebootModulePkg/CbSupportPei: Mask off all legacy 8259 interrupt sources

The current coreboot UEFI payload has an assumption that all interrupt
sources should be masked off before transferring control to the payload.
However, it is not the case on some platforms, such as QEMU. It will
cause boot failure due to unexpected pending interrupt in the payload.

To resolve it all legacy 8259 interrupt sources need to be masked
piror to the DXE phase. The fix was tested on QEMU virtual platform.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Maurice Ma <maurice.ma@intel.com>
Reviewed-by: Prince Agyeman <prince.agyeman@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17550 6f19259b-4bc3-4df7-8a09-765794883524