ARM: Orion: WDT: Add clk/clkdev support

Remove tclk from platform data.  This makes the platform data
structure 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>