KVM: arm64: Explicitly trap unsupported HFGxTR_EL2 features

Do not rely on the value of __HFGRTR_EL2_nMASK to trap
unsupported features, since the nMASK can (and will) change as
new traps are added and as its value is updated. Instead,
explicitly specify the trap bits.

Suggested-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231214100158.2305400-6-tabba@google.com