PeCoffExtraActionLibDebug: Restore debug registers in PeCoffExtraActionLibDebug

PeCoffExtraActionLibDebug: Restore debug registers in PeCoffExtraActionLibDebug

PeCoffExtraActionLibDebug uses the debug registers to pass module load information to the
DebugAgent, then restores the old register values.
However, it was missing code to restore Dr7 in the
DEBUG_LOAD_IMAGE_METHOD_SOFT_INT3 case.  This broke hardware breakpoints and watchpoints.
It could also lose modifications the debugger made to Cr4.

Restore the Dr7 and Cr4 values correctly in the
DEBUG_LOAD_IMAGE_METHOD_SOFT_INT3 case, as well as the
DEBUG_LOAD_IMAGE_METHOD_IO_HW_BREAKPOINT case.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Brian J. Johnson <bjohnson@sgi.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17071 6f19259b-4bc3-4df7-8a09-765794883524