Add cpufreq support for DaVinci I2C driver.
Tested on DA850/OMAP-L138 EVM. For the purpose of testing, the patches
which add cpufreq support [1] for this SoC are needed.

[1]http://linux.davincidsp.com/pipermail/davinci-linux-open-source/
2009-September/016118.html
Signed-off-by: Chaithrika U S <chaithrika@ti.com>
Acked-by: Kevin Hilman <khilman@deeprootsystems.com>