x86: use standard PIT frequency

the RDC and ELAN platforms use slighly different PIT clocks, resulting in
a timex.h hack that changes PIT_TICK_RATE during build time. But if a
tester enables any of these platform support .config options, the PIT
will be miscalibrated on standard PC platforms.

So use one frequency - in a subsequent patch we'll add a quirk to allow
x86 platforms to define different PIT frequencies.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/include/asm/timex.h

-/* x86 architecture timex specifications */
 #ifndef _ASM_X86_TIMEX_H
 #define _ASM_X86_TIMEX_H
 
 #include <asm/processor.h>
 #include <asm/tsc.h>
 
-#ifdef CONFIG_X86_ELAN
-#  define PIT_TICK_RATE 1189200 /* AMD Elan has different frequency! */
-#elif defined(CONFIG_X86_RDC321X)
-#  define PIT_TICK_RATE 1041667 /* Underlying HZ for R8610 */
-#else
-#  define PIT_TICK_RATE 1193182 /* Underlying HZ */
-#endif
-#define CLOCK_TICK_RATE	PIT_TICK_RATE
+/* The PIT ticks at this frequency (in HZ): */
+#define PIT_TICK_RATE		1193182
+
+#define CLOCK_TICK_RATE		PIT_TICK_RATE
 
 #define ARCH_HAS_READ_CURRENT_TIMER