ARM Packages: Force the SEC modules to be 2K aligned for AArch64

ARM Packages: Force the SEC modules to be 2K aligned for AArch64

The AArch64 Vector Table must be aligned on a 2K boundary.
The FDF specification does not support 2K alignment but support 4K.

A clear comment has been added to help integrator to understand why the
assertion fails when porting to a new AArch64 platform.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Olivier Martin <olivier.martin@arm.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15659 6f19259b-4bc3-4df7-8a09-765794883524