Tegra: console clock settings for real/FPGA platforms

Tegra: console clock settings for real/FPGA platforms

This patch sets up the clock for the UART console, for real Silicon
and FPGA platforms. FPGA platforms run the UART clock source at
13MHz, whereas the clock cource runs at 408MHz for real silicon.

Change-Id: Ibfd99df032ec473f29e636e597cfc95a0f580598
Signed-off-by: Harvey Hsieh <hhsieh@nvidia.com>
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>