KVM: arm64: nv: Expose BTI and CSV_frac to a guest hypervisor

KVM: arm64: nv: Expose BTI and CSV_frac to a guest hypervisor

Now that we expose PAC to NV guests, we can also expose BTI (as
the two as joined at the hip, due to some of the PAC instructions
being landing pads).

While we're at it, also propagate CSV_frac, which requires no
particular emulation.

Fixes: f4f6a95bac49 ("KVM: arm64: nv: Advertise support for PAuth")
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240528100632.1831995-3-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>