clk: pxa: pxa3xx: add missing os timer clock

The pxa3xx scheduler relies on the pxa-timer, which requires a clock for
its rate. As the clock handling will be taken over by the clock
framework, add this missing clock.

The miss was discovered by attempting to run a zylonite platform in a
device-tree configuration, with the future patch to shift clocks
handling to clock framework applied.

Signed-off-by: Robert Jarzmik <[e-mail]>
Signed-off-by: Michael Turquette <[e-mail]>

drivers/clk/pxa/clk-pxa3xx.c

···
 	clk_register_clk_pxa3xx_smemc();
 	clk_register_gate(NULL, "CLK_POUT", "osc_13mhz", 0,
 			  (void __iomem *)&OSCC, 11, 0, NULL);
+	clkdev_pxa_register(CLK_OSTIMER, "OSTIMER0", NULL,
+			    clk_register_fixed_factor(NULL, "os-timer0",
+						      "osc_13mhz", 0, 1, 4));
 }
 
 int __init pxa3xx_clocks_init(void)