interrupts: Ack/fetch interrupts in reset_cpu_icp()
interrupts: Ack/fetch interrupts in reset_cpu_icp()

This does a fetch from the XIRR, thus acking any pending interrupt
before we clear IPIs and EOI. This mimmics a real sequence better
and works around problems on some sims (and possibly hardware)
where just raising MFRR won't lower the IRQ line to the CPU.

Signed-off-by: Benjamin Herrenschmidt <a7089bb6e7e92505d88aaff006cbdd60cc9120b6@kernel.crashing.org>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

legoater/skiboot,stewart-ibm/skiboot,qemu/skiboot,shenki/skiboot,mikey/skiboot,legoater/skiboot,qemu/skiboot,qemu/skiboot,legoater/skiboot,qemu/skiboot,mikey/skiboot,shenki/skiboot,shenki/skiboot,stewart-ibm/skiboot,stewart-ibm/skiboot,legoater/skiboot,open-power/skiboot,shenki/skiboot,open-power/skiboot,qemu/skiboot,open-power/skiboot,legoater/skiboot,open-power/skiboot,shenki/skiboot,open-power/skiboot,mikey/skiboot