asm-generic: move parts of Arm's asm/kernel.h to common code

asm-generic: move parts of Arm's asm/kernel.h to common code

Move the following parts to common with the following changes:
- struct kernel_info:
  - Create arch_kernel_info for arch specific kernel information.
    At the moment, it contains domain_type for Arm.
  - s/phandle_gic/phandle_intc to have more generic name suitable for other
    archs.
  - Make text_offset of zimage structure available for RISCV_64.
- Wrap by `#ifdef KERNEL_INFO_SHM_MEM_INIT` definition of KERNEL_SHM_MEM_INIT
  and wrap by `#ifndef KERNEL_INFO_INIT` definition of KERNEL_INFO_INIT to have
  ability to override KERNEL_INFO_SHM_MEM_INIT for arch in case it doesn't
  want to use generic one.
- Move DOM0LESS_* macros to dom0less-build.h.
- Move all others parts of Arm's kernel.h to xen/fdt-kernel.h.

Because of the changes in struct kernel_info the correspondent parts of Arm's
code are updated.

As part of this patch the following clean up happens:
- Drop asm/setup.h from asm/kernel.h as nothing depends from it.
  Add inclusion of asm/setup.h for a code which uses device_tree_get_reg() to
  avoid compilation issues for CONFIG_STATIC_MEMORY and CONFIG_STATIC_SHM.
- Drop inclusion of asm/kernel.h everywhere except xen/fdt-kernel.h.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>