xen/common: dom0less: introduce common dom0less-build.c

xen/common: dom0less: introduce common dom0less-build.c

Part of Arm's dom0less-build.c could be common between architectures which are
using device tree files to create guest domains. Thereby move some parts of
Arm's dom0less-build.c to common code with minor changes.

As a part of theses changes the following changes are introduced:
- Introduce make_arch_nodes() to cover arch-specific nodes. For example, in
  case of Arm, it is PSCI and vpl011 nodes.
- Introduce set_domain_type() to abstract a way how setting of domain type
  happens. For example, RISC-V won't have this member of arch_domain structure
  as vCPUs will always have the same bitness as hypervisor. In case of Arm, it
  is possible that Arm64 could create 32-bit and 64-bit domains.
- Introduce init_vuart() to cover details of virtual uart initialization.
- Introduce init_intc_phandle() to cover some details of interrupt controller
  phandle initialization. As an example, RISC-V could have different name for
  interrupt controller node ( APLIC, PLIC, IMSIC, etc ) but the code in
  domain_handle_dtb_bootmodule() could handle only one interrupt controller
  node name.
- s/make_gic_domU_node/make_intc_domU_node as GIC is Arm specific naming and
  add prototype of make_intc_domU_node() to dom0less-build.h

The following functions are moved to xen/common/device-tree:
- Functions which are moved as is:
  - domain_p2m_pages().
  - handle_passthrough_prop().
  - handle_prop_pfdt().
  - scan_pfdt_node().
  - check_partial_fdt().
- Functions which are moved with some minor changes:
  - alloc_xenstore_evtchn():
    - ifdef-ing by CONFIG_HVM accesses to hvm.params.
  - prepare_dtb_domU():
    - ifdef-ing access to gnttab_{start,size} by CONFIG_GRANT_TABLE.
    - s/make_gic_domU_node/make_intc_domU_node.
    - Add call of make_arch_nodes().
- domain_handle_dtb_bootmodule():
  - hide details of interrupt controller phandle initialization by calling
    init_intc_phandle().
  - Update the comment above init_intc_phandle(): s/gic/interrupt controller.
- construct_domU():
  - ifdef-ing by CONFIG_HVM accesses to hvm.params.
  - Call init_vuart() to hide Arm's vpl011_init() details there.
  - Add call of set_domain_type() instead of setting kinfo->arch.type explicitly.

Some parts of dom0less-build.c are wraped by #ifdef CONFIG_STATIC_{SHMEM,MEMORY}
as not all archs support these configs.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
[stefano: fix code style]
Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>