OvmfPkg: Consume new alignment-related macros

This patch substitutes the macros that were renamed in the second
patch with the new, shared alignment macros.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Jiewen Yao <Jiewen.yao@intel.com>
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>