davinci: enable ARCH_HAS_HOLES_MEMORYMODEL for DaVinci

All DaVinci platforms include a DSP or co-processor for
audio/video acceleration.

While creating memory for the DSP/co-processor, system
integrator can end up creating a hole in the memory map
of the sort:

<kernel memory> <hole (memory for DSP)> <kernel memory>

This sort of configuration needs ARCH_HAS_HOLES_MEMORYMODEL
enabled. See further details see this discussion on ARM
linux mailing list:
http://www.mail-archive.com/linux-omap@vger.kernel.org/msg15262.html

The patch is boot tested on OMAP-L138, DM6446 and DM355 EVMs

Signed-off-by: Sekhar Nori <nsekhar@ti.com>
CC: Sriramakrishnan <srk@ti.com>
CC: Khasim Syed Mohammed <khasim@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>