KVM: PPC: select IRQ_BYPASS_MANAGER

Select IRQ_BYPASS_MANAGER for PPC when CONFIG_KVM is set.
Add the PPC producer functions for add and del producer.

[paulus@ozlabs.org - Moved new functions from book3s.c to powerpc.c
 so booke compiles; added kvm_arch_has_irq_bypass implementation.]

Signed-off-by: Suresh Warrier <warrier@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>