KVM: PPC: Fix misleading interrupts comment in kvmppc_prepare_to_enter()

Until commit 6c85f52b ("kvm/ppc: IRQ disabling cleanup"),
kvmppc_prepare_to_enter() was called with interrupts already disabled by
the caller, which was documented in the comment above the function.

Post-cleanup, the function is now called with interrupts enabled, and
disables interrupts itself.

Fix the comment to reflect the current behaviour.

Fixes: 6c85f52b ("kvm/ppc: IRQ disabling cleanup")
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Reviewed-by: Amit Machhiwal <amachhiw@linux.ibm.com>
Reviewed-by: Gautam Menghani <gautam@linux.ibm.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
[Fixed the double colon in Reviewed-by line]
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250806055607.17081-1-ajd@linux.ibm.com