ARM: mxs: use CLKSRC_OF helper to initialize timer

Select CLKSRC_OF and use clocksource_of_init() to initialize timer, so
that the call to mxs_timer_init() in clock driver can be removed.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

drivers/clk/mxs/clk-imx28.c

@@ -15,7 +15,6 @@
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/of.h>
-#include <mach/common.h>
 #include <mach/mx28.h>
 #include "clk.h"
 
@@ -244,7 +243,5 @@ int __init mx28_clocks_init(void)
 	for (i = 0; i < ARRAY_SIZE(clks_init_on); i++)
 		clk_prepare_enable(clks[clks_init_on[i]]);
 
-	mxs_timer_init();
-
 	return 0;
 }