davinci: Add base DA850/OMAP-L138 SoC support

The DA850/OMAP-L138 is a new SoC from TI in the same family as
DA830/OMAP-L137.

Major changes include better support for power management,
support for SATA devices and McBSP (same IP as DM644x).

DA850/OMAP-L138 documents are available at
http://focus.ti.com/docs/prod/folders/print/omap-l138.html

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Signed-off-by: Sudhakar Rajashekhara <sudhakar.raj@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>