cpufreq: intel_pstate: Drop INTEL_PSTATE_HWP_SAMPLING_INTERVAL

After commit 62611cb9 (intel_pstate: delete scheduler hook in HWP
mode) the INTEL_PSTATE_HWP_SAMPLING_INTERVAL is not used anywhere in
the code, so drop it.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/intel_pstate.c

@@ -38,7 +38,6 @@
 #include <asm/intel-family.h>
 
 #define INTEL_PSTATE_DEFAULT_SAMPLING_INTERVAL	(10 * NSEC_PER_MSEC)
-#define INTEL_PSTATE_HWP_SAMPLING_INTERVAL	(50 * NSEC_PER_MSEC)
 
 #define INTEL_CPUFREQ_TRANSITION_LATENCY	20000
 #define INTEL_CPUFREQ_TRANSITION_DELAY		500