x86/kconfig: Move the ZONE_DMA entry under a menu

Move the ZONE_DMA kconfig symbol under a menu item instead
of having it listed before everything else in
"make {xconfig | gconfig | nconfig | menuconfig}".

This drops the first line of the top-level kernel config menu
(in 3.2) below and moves it under "Processor type and features".

          [*] DMA memory allocation support
              General setup  --->
          [*] Enable loadable module support  --->
          [*] Enable the block layer  --->
              Processor type and features  --->
              Power management and ACPI options  --->
              Bus options (PCI etc.)  --->
              Executable file formats / Emulations  --->

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-mm@kvack.org <linux-mm@kvack.org>
Link: http://lkml.kernel.org/r/4F14811E.6090107@xenotime.net


Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: David Rientjes <rientjes@google.com>