KVM: arm64: nv: Fix MI line level calculation in vgic_v3_nested_update_mi()

KVM: arm64: nv: Fix MI line level calculation in vgic_v3_nested_update_mi()

The state of the vcpu's MI line should be asserted when its
ICH_HCR_EL2.En is set and ICH_MISR_EL2 is non-zero. Using bitwise AND
(&=) directly for this calculation will not give us the correct result
when the LSB of the vcpu's ICH_MISR_EL2 isn't set. Correct this by
directly computing the line level with a logical AND operation.

Signed-off-by: Wei-Lin Chang <r09922117@csie.ntu.edu.tw>
Link: https://lore.kernel.org/r/20250625084709.3968844-1-r09922117@csie.ntu.edu.tw
[maz: drop the level check from the original code]
Signed-off-by: Marc Zyngier <maz@kernel.org>