SourceLevelDebugPkg/SmmDebugAgent: Initialize Local APIC Timer

SourceLevelDebugPkg/SmmDebugAgent: Initialize Local APIC Timer

Now Debug Agent library uses Local APIC Timer to implement time-out mechanism.
In SMM, SMM BSP maybe not be the one in DXE phase, its local APIC timer may not
work. This fix is to initialize Local APIC timer if it doesn't work as expected
at SMM entry.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17500 6f19259b-4bc3-4df7-8a09-765794883524