ARM: Orion: Add clocks using the generic clk infrastructure.

Add tclk as a fixed rate clock for all platforms. In addition, on
kirkwood, add a gated clock for most of the clocks which can be gated.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Jamie Lentin <jm@lentin.co.uk>
[mturquette@linaro.org: removed redundant CLKDEV_LOOKUP from Kconfig]
[mturquette@linaro.org: removed redundant clk.h from mach-dove/common.c]
Signed-off-by: Mike Turquette <mturquette@linaro.org>