[ARM] arm32ve: Fix HTCR and VTCR programing

Currently, we did not explicitly clear crucial fields of HTCR
and VTCR before re-programing new values in them.

This patch improves and fixes HTCR and VTCR programing. We also
update HTCR and VTCR programing to ensure cacheable + write-back
translation table walks for hypervisor stage1 and stage2.

Signed-off-by: Anup Patel <anup@brainfault.org>