ARM: Orion: SPI: Add clk/clkdev support.

Remove now redundant tclk from SPI platform data. This makes the platform
data empty, so remove it.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Jamie Lentin <jm@lentin.co.uk>
Signed-off-by: Mike Turquette <mturquette@linaro.org>