omap2+: Use dmtimer macros for clockevent

This patch makes timer-gp.c to use only a subset of dmtimer
functions without the need to initialize dmtimer code early.

Also note that now with the inline functions, timer_set_next_event
becomes more efficient in the lines of assembly code.

Signed-off-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>

arch/arm/plat-omap/include/plat/dmtimer.h

@@ -216,6 +216,7 @@ struct omap_dm_timer {
 	struct clk *iclk, *fclk;
 #endif
 	void __iomem *io_base;
+	unsigned long rate;
 	unsigned reserved:1;
 	unsigned enabled:1;
 	unsigned posted:1;