ARM: Kirkwood: Ensure runit clock always ticks.

Marvell engineers tell us:

	It seems that many units use the RUNIT clock.
	SPI, UART, NAND, TWSI, ...
	So it's not possible to clock gate it.

Currently the SPI, NAND and TWSI driver will clk_prepaure_enable()
this clk, but since we have no idea what ... is, and turning this clk
off results in a hard lock, unconditionally enable runit.
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Tested-by: NSimon Baatz <gmbnomis@gmail.com>

arch/arm/mach-kirkwood/common.c

@@ -241,6 +241,11 @@ void __init kirkwood_clk_init(void)
 	orion_clkdev_add("0", "pcie", pex0);
 	orion_clkdev_add("1", "pcie", pex1);
 	orion_clkdev_add(NULL, "kirkwood-i2s", audio);
+
+	/* Marvell says runit is used by SPI, UART, NAND, TWSI, ...,
+	 * so should never be gated.
+	 */
+	clk_prepare_enable(runit);
 }
 
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