ArmPkg/ArmLib: Correct Error Handling in AArch64

ArmPkg/ArmLib: Correct Error Handling in AArch64

There are several instances of asserts which do not also handle
the error condition in Release builds.
Because these functions are called in different location of the
code and their parameters might change during the execution, it
is safer to handle the error.

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@15399 6f19259b-4bc3-4df7-8a09-765794883524