KVM: arm64: Compute vgic state irrespective of the number of interrupts

KVM: arm64: Compute vgic state irrespective of the number of interrupts

As we are going to rely on the [G]ICH_HCR{,_EL2} register to be
programmed with MI information at all times, slightly de-optimise
the flush/sync code to always be called. This is rather lightweight
when no interrupts are in flight.

Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Link: https://msgid.link/20251120172540.2267180-20-maz@kernel.org
Signed-off-by: Oliver Upton <oupton@kernel.org>