ArmVirtualizationPkg: expose debug message bitmask on build command line

ArmVirtualizationPkg: expose debug message bitmask on build command line

This enables -D DEBUG_PRINT_ERROR_LEVEL=0x8040004F style command line
options.

Since we're massaging the debug message bitmask anyway, let's update the
description of the individual bits too in the comments, so that they match
"MdePkg/Include/Library/DebugLib.h".

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@arm.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16986 6f19259b-4bc3-4df7-8a09-765794883524