memblock: add memblock_cap_memory_range()

Add memblock_cap_memory_range() which will remove all the memblock regions
except the memory range specified in the arguments. In addition, rework is
done on memblock_mem_limit_remove_map() to re-implement it using
memblock_cap_memory_range().

This function, like memblock_mem_limit_remove_map(), will not remove
memblocks with MEMMAP_NOMAP attribute as they may be mapped and accessed
later as "device memory."
See the commit a571d4eb55d8 ("mm/memblock.c: add new infrastructure to
address the mem limit issue").

This function is used, in a succeeding patch in the series of arm64 kdump
suuport, to limit the range of usable memory, or System RAM, on crash dump
kernel.
(Please note that "mem=" parameter is of little use for this purpose.)

Signed-off-by: AKASHI Takahiro <[email protected]>
Reviewed-by: Will Deacon <[email protected]>
Acked-by: Catalin Marinas <[email protected]>
Acked-by: Dennis Chen <[email protected]>
Cc: [email protected]
Cc: Andrew Morton <[email protected]>
Reviewed-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Catalin Marinas <[email protected]>

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