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Signed-off-by: Gerwin Klein <gerwin.klein@data61.csiro.au>

libsel4vm: Update documentation

This commit refreshes the interface documentation in libsel4vm.
This commit patches in missing documentation and additionally
ensures all interface documentation conforms to Doxygen style
comments.

libsel4vm: Remove allocman dependency

allocman is an object allocation manager that provides an implementation
of the `vka_t` interface. As libsel4vm can perform all allocation
through the `vka_t` interface, it doesn't need to know about allocman.
This commit also adds some missing #includes for dependencies that were
being originally included through the allocman header.

libsel4vm: Helper to assign target cpu val to vcpu

Added a helper that updates a vcpu with a target_cpu value. This
is a basic setter utility that additionally ensure two vcpus
aren't assigned to the same target

libsel4vm: MAX_NUM_VCPUS -> CONFIG_MAX_NUM_NODES

Replace usages of 'MAX_NUM_VCPUS' with 'CONFIG_MAX_NUM_NODES' as
this directly correlates with the number of cores made available.
This in addition avoids the need of having to allocate the VM's
vcpus array.

trivial: Style changed files

libsel4vm: Fixup includes and clean cmake file

Organise CMakeLists.txt file to be consistent with other projects.

libsel4vm: Removed vpcu_init cookie parameter

This parameter has never been needed or used hence we can remove
it.

libsel4vm: Removed vm_init cookie for arch params

Removed architecture specific vm initialisation params as both
architecture sources no longer need to pass in specific
parameters. This additionally means we can delete the 'cookie'
parameter since its no longer used.

libsel4vm: Consolidate notification/fault endpoint

Both arm and x86 source take in the hosts own endpoint such that
it can wait on it for notifications and events. Removed the
passing of the endpoint as an arch specfic boot parameter as
its now passed through the common vm_init function.

libsel4vm: Moved VM tcb object into vcpu object

There is a strong association between a VCPU and the TCB it is
binded to. Thus the TCB object should exist in the context of the
VCPU it is associated with. In addition this makes the VM library
open to possible SMP extensions. This commit updates the
initialisation of the TCB object when creating a VCPU and
the means of accessing TCB objects.

libsel4vm: Fixed vcpu typo

Fixed "vpcu's" usages. Now 'vpcu'.

libsel4vm: Removed vm_plat_callbacks

Due to the async notification callback being refactored to a new
location, the vm_plat_callbacks is only relevant to x86 source
code. This has been refactored to a x86 specific configuration
datastructure.

libsel4vm: Simplified vm_create_vcpu interface

Made the vcpu creation interface easier to use. It now returns
an allocated vm_vpcu object with a sequential id. This removes
the requirement for the user to supply a vcpu id and a vcpu
pointer to allocate.

libsel4vm: Made arch_init functions private

Refactored the architecture specific init/boot functions into a
private interface. These are no needed in the public boot.h
interface.

libsel4vm: vm data-structure initialisation

Refactored the x86 and arm initialisation of the guest vm
data-structure. This brings the initialisation of the
vm data structure under the one interface 'sel4vm/boot.h'.