davinci: add support for DM6467T EVM

DM6467T (T for Turbo) is a newer and faster DM6467
part from TI. The new part supports 1080p video and
has the ARM running at 495MHz. More SoC information:

http://focus.ti.com/docs/prod/folders/print/tms320dm6467t.html



Spectrum Digital, Inc has a new EVM for this part.
It is _mostly_ same as the older DM6467 EVM except
for a 33MHz crystal input and THS8200 video encoder
for 1080p support.

The meat of this patch is dedicated to initializing
the crystal frequency from EVM board file.

Additional notes:
I did consider some alternative ways to make the crystal
input board specific including - (1) having board code
initialize the crystal frequency using the first member
of soc_info->cpu_clks array (2) introducing a new ref_clk_rate
member in soc_info structure.

But, the current way seems to be the simplest and least
intruding considering that both the clock array and SoC
info structure are actually private to the SoC file. Also
the fact that davinci_common_init() initializes both the
soc_info and clocks in one go.

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