mpipl: Disable fast-reboot during post MPIPL boot
mpipl: Disable fast-reboot during post MPIPL boot

Otherwise device tree will continue to have `mpipl-boot` and kernel may
think its MPIPL boot.

Signed-off-by: Vasant Hegde <a6d753843573f7bfed5075c1e875b0be8007a0ab@linux.vnet.ibm.com>
Reviewed-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@flamingspork.com>
Signed-off-by: Oliver O'Halloran <3dfaff8fa6ae977f042064a112a6aac576279b9b@gmail.com>

open-power/skiboot,open-power/skiboot,shenki/skiboot,shenki/skiboot,qemu/skiboot,open-power/skiboot,legoater/skiboot,qemu/skiboot,legoater/skiboot,legoater/skiboot,qemu/skiboot,open-power/skiboot,shenki/skiboot,qemu/skiboot,open-power/skiboot,shenki/skiboot,legoater/skiboot,qemu/skiboot,shenki/skiboot,legoater/skiboot