memory hotplug: small fixes to bootmem freeing for memory hotremove

memory hotplug: small fixes to bootmem freeing for memory hotremove

- Change some naming
  * Magic -> types
  * MIX_INFO -> MIX_SECTION_INFO
  * Change definition of bootmem type from direct hex value

- __free_pages_bootmem() becomes __meminit.

Signed-off-by: Yasunori Goto <[email protected]>
Cc: Andy Whitcroft <[email protected]>
Cc: Badari Pulavarty <[email protected]>
Cc: Yinghai Lu <[email protected]>
Cc: Johannes Weiner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>