ppc/kvm: Use error_report() instead of cpu_abort() for user-triggerable errors

ppc/kvm: Use error_report() instead of cpu_abort() for user-triggerable errors

Setting the KVM_CAP_PPC_PAPR capability can fail if either the KVM
kernel module does not support it, or if the specified vCPU type
is not a 64-bit Book3-S CPU type. For example, the user can trigger
it easily with "-M pseries -cpu G2leLS" when using the kvm-pr kernel
module. So the error should not be reported with cpu_abort() since
this function is rather meant for reporting programming errors than
reporting user-triggerable errors (it prints out all CPU registers
and then calls abort() to kills the program - two things that the
normal user does not expect here) . So let's use error_report() with
exit(1) here instead.
A similar problem exists in the code that sets the KVM_CAP_PPC_EPR
capability, so while we're at it, fix that, too.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>