linux-imx

of: Add vendor prefix for Cadence

Drivers like clocksource/cadence_ttc and net/macb already use the 'cdns'
prefix for Cadence IP.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>