ARM: dts: sirf: fix fifosize, clks, dma channels for UART

sirf uart and usp-based uart driver with full dma support has
hit 3.12, here we fix the fifosize, dma channels for some HW
prop.

Signed-off-by: Qipan Li <Qipan.Li@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Olof Johansson <olof@lixom.net>