iommu: setup inclusive mappings before enabling iommu

iommu: setup inclusive mappings before enabling iommu

Or else it can lead to freezes when enabling the iommu on certain
Intel hardware:

[...]
(XEN) ELF: addresses:
(XEN)     virt_base        = 0xffffffff80000000
(XEN)     elf_paddr_offset = 0x0
(XEN)     virt_offset      = 0xffffffff80000000
(XEN)     virt_kstart      = 0xffffffff81000000
(XEN)     virt_kend        = 0xffffffff82953000
(XEN)     virt_entry       = 0xffffffff8274e180
(XEN)     p2m_base         = 0x8000000000
(XEN)  Xen  kernel: 64-bit, lsb, compat32
(XEN)  Dom0 kernel: 64-bit, PAE, lsb, paddr 0x1000000 -> 0x295300
<freeze>

This restores the behavior before commit 66a9274cc3435 that changed
the order and enabled the iommu without having the inclusive mappings
setup.

Note that on AMD hardware the order is also changed to add inclusive
mappings before adding any devices.

Reported-by: Dario Faggioli <dfaggioli@suse.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Tested-by: Dario Faggioli <dfaggioli@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Julien Grall <julien.grall@arm.com>