Provide the name of each memblock type with struct memblock_type.  This
allows to get rid of the function memblock_type_name() and duplicating
the type names in __memblock_dump_all().

The only memblock_type usage out of mm/memblock.c seems to be
arch/s390/kernel/crash_dump.c.  While at it, give it a name.

Link: http://lkml.kernel.org/r/20170120123456.46508-4-heiko.carstens@de.ibm.comSigned-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Philipp Hachtmann <phacht@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>