[PATCH v13 04/16] powerpc, kexec_file: factor out memblock-based arch_kexec_walk_mem()

Memblock list is another source for usable system memory layout. So move powerpc's arch_kexec_walk_mem() to common code so that other memblock-based architectures, particularly arm64, can also utilise it. A moved function is now renamed to kexec_walk_memblock() and integrated into

[PATCH v13 04/16] powerpc, kexec_file: factor out memblock-based arch_kexec_walk_mem()

Memblock list is another source for usable system memory layout. So move powerpc's arch_kexec_walk_mem() to common code so that other memblock-based architectures, particularly arm64, can also utilise it. A moved function is now renamed to kexec_walk_memblock() and integrated into