ArmPkg: Convert whole-cache InvalidateInstructionCache to just ASSERT

ArmPkg: Convert whole-cache InvalidateInstructionCache to just ASSERT

In SVN 18756 ("disallow whole D-cache maintenance operations")
InvalidateInstructionCache was modified to remove the full data cache
clean but left the full instruction cache invalidate. The change was
made to address issues in the set/way clean methodology but the
resulting code could lead someone to a painful debug. If a component
called this function, the proper code would not be flushed to the PoU,
since the intent of this function is not only to invalidate the I-cache
but to provide coherency after code loading / modification. This change
simply places an ASSERT(FALSE) in this function to avoid this hazard.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Eugene Cohen <eugene@hp.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19084 6f19259b-4bc3-4df7-8a09-765794883524