x86/hpet: Remove unused FSEC_PER_NSEC define

The FSEC_PER_NSEC macro has had zero users since commit

  ab0e08f1 ("x86: hpet: Cleanup the clockevents init and register code").

Remove it.
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20181130211450.5200-1-roland@purestorage.com

arch/x86/kernel/hpet.c

@@ -21,10 +21,6 @@
 
 #define HPET_MASK			CLOCKSOURCE_MASK(32)
 
-/* FSEC = 10^-15
-   NSEC = 10^-9 */
-#define FSEC_PER_NSEC			1000000L
-
 #define HPET_DEV_USED_BIT		2
 #define HPET_DEV_USED			(1 << HPET_DEV_USED_BIT)
 #define HPET_DEV_VALID			0x8