davinci: Initial support for MityDSP-L138/MityARM-1808

This patch adds initial support for the MityDSP-L138 and MityDSP-1808 system
on Module (SOM) under the machine name "mityomapl138".  These SOMs are based
on the da850 davinci CPU architecture.  Information on these SOMs may be
found at http://www.mitydsp.com

.

Basic support for the console UART, NAND, and EMAC (MII interface) is
included in this patch.

Signed-off-by: Michael Williamson <michael.williamson@criticallink.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>