ARM: u300: convert to common clock

This converts the U300 clock implementation over to use the common
struct clk and moves the implementation down into drivers/clk.
Since VCO isn't used in tree it was removed, it's not hard to
put it back in if need be.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
[mturquette@linaro.org: trivial Makefile conflict]
Signed-off-by: Mike Turquette <mturquette@linaro.org>

arch/arm/mach-u300/timer.c

@@ -354,7 +354,7 @@ static void __init u300_timer_init(void)
 	/* Clock the interrupt controller */
 	clk = clk_get_sys("apptimer", NULL);
 	BUG_ON(IS_ERR(clk));
-	clk_enable(clk);
+	clk_prepare_enable(clk);
 	rate = clk_get_rate(clk);
 
 	setup_sched_clock(u300_read_sched_clock, 32, rate);