memblock: embed memblock type name within struct memblock_type

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.com
Signed-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>

arch/s390/kernel/crash_dump.c

@@ -32,6 +32,7 @@ static struct memblock_type oldmem_type = {
 	.max = 1,
 	.total_size = 0,
 	.regions = &oldmem_region,
+	.name = "oldmem",
 };
 
 struct save_area {