davinci: add CDCE949 support on DM6467 EVM

This patch adds the CDCE949 reference oscillator to
the davinci clock list.

On the DM6467T EVM, the CDCE949 is responsible for
generating the pixel clock for display. On the DM6467
EVM, this pixel clock was being obtained from an
internal source. This is not possible on the DM6467T
EVM because of the presence of a 33MHz oscillator.

The TSIF module also requires the CDCE949 to generate
the data clocks.

The actual clock definitions will be added by patches
adding support for DM6467T VPIF and TSIF. This patch
mearly lays the foundation for that work.

Signed-off-by: Nageswari Srinivasan <nageswari@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>