ARM: ixp4xx: stop using <mach/timex.h>

The only user of symbols defined in ixp4xx's <mach/timex.h> is common.c.
Fix that one up by moving the used #define into common.c directly and
add a local substitute for the global define LATCH which uses
CLOCK_TICK_RATE. This makes ixp4xx not to be a bar to dropping support
for <mach/timex.h>.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

arch/arm/mach-ixp4xx/common.c

@@ -23,7 +23,6 @@
 #include <linux/interrupt.h>
 #include <linux/bitops.h>
 #include <linux/time.h>
-#include <linux/timex.h>
 #include <linux/clocksource.h>
 #include <linux/clockchips.h>
 #include <linux/io.h>
@@ -45,6 +44,9 @@
 #include <asm/mach/irq.h>
 #include <asm/mach/time.h>
 
+#define IXP4XX_TIMER_FREQ 66666000
+#define IXP4XX_LATCH DIV_ROUND_CLOSEST(IXP4XX_TIMER_FREQ, HZ)
+
 static void __init ixp4xx_clocksource_init(void);
 static void __init ixp4xx_clockevent_init(void);
 static struct clock_event_device clockevent_ixp4xx;
@@ -520,7 +522,7 @@ static void ixp4xx_set_mode(enum clock_event_mode mode,
 
 	switch (mode) {
 	case CLOCK_EVT_MODE_PERIODIC:
-		osrt = LATCH & ~IXP4XX_OST_RELOAD_MASK;
+		osrt = IXP4XX_LATCH & ~IXP4XX_OST_RELOAD_MASK;
  		opts = IXP4XX_OST_ENABLE;
 		break;
 	case CLOCK_EVT_MODE_ONESHOT: