xen/arm: introduce xen_early_init, use PSCI on xen

Split xen_guest_init in two functions, one of them (xen_early_init) is
going to be called very early from setup_arch.

Change machine_desc->smp_init to xen_smp_init if Xen is present on the
platform. xen_smp_init just sets smp_ops to psci_smp_ops.

XEN selects ARM_PSCI.

Changes in v6:
- xen_smp_init: call smp_set_ops only ifdef CONFIG_SMP;
- move more of the initialization to xen_guest_init;
- select ARM_PSCI if XEN.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
4 files changed