i8253: Consolidate definitions of PIT_LATCH

i8253: Consolidate definitions of PIT_LATCH

x86 defines PIT_LATCH as LATCH which in <linux/timex.h> is defined as
((CLOCK_TICK_RATE + HZ/2) / HZ) and <asm/timex.h> again defines
CLOCK_TICK_RATE as PIT_TICK_RATE.

MIPS defines PIT_LATCH as LATCH which in <linux/timex.h> is defined as
((CLOCK_TICK_RATE + HZ/2) / HZ) and <asm/timex.h> again defines
CLOCK_TICK_RATE as 1193182.

ARM defines PITCH_LATCH as ((PIT_TICK_RATE + HZ / 2) / HZ) - and that's
the sanest thing and equivalent to above definitions so use that as the
new definition in <linux/i8253.h>.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@linux-mips.org
Link: http://lkml.kernel.org/r/20110601180610.832810002@duck.linux-mips.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>