KVM: arm64: vgic: Drop stale comment on IRQ active state

KVM: arm64: vgic: Drop stale comment on IRQ active state

While LPIs lack an active state, KVM unconditionally folds the active
state from the LR into the vgic_irq struct meaning this field cannot be
'creatively' reused for something else.

Drop the misleading comment to reflect this.

Link: https://lore.kernel.org/r/20250905100531.282980-2-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>