ANDROID: KVM: arm64: Set unknown bits of VBAR_EL1

According to the architecture spec, the value of VBAR_EL1 is mostly
unknown. Set those unknown bits to an easily recognizable value. These
registers are often some of the more problematic registers when it comes
to debugging, and therefore having that value would aid in debugging a
guest.

Bug: 433902668
Change-Id: Ia3c217aff9dbb5aec91e41a27c361a106ff68d19
Signed-off-by: Fuad Tabba <tabba@google.com>