cpufreq: intel_pstate: fix struct cpudata::epp_cached kernel-doc

make C=1 currently gives the following warning:

drivers/cpufreq/intel_pstate.c:262: warning: Function parameter or struct member 'epp_cached' not described in 'cpudata'

Add the missing ":" to fix the trivial kernel-doc syntax error.
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/intel_pstate.c

@@ -211,7 +211,7 @@ struct global_params {
  * @epp_policy:		Last saved policy used to set EPP/EPB
  * @epp_default:	Power on default HWP energy performance
  *			preference/bias
- * @epp_cached		Cached HWP energy-performance preference value
+ * @epp_cached:		Cached HWP energy-performance preference value
  * @hwp_req_cached:	Cached value of the last HWP Request MSR
  * @hwp_cap_cached:	Cached value of the last HWP Capabilities MSR
  * @last_io_update:	Last time when IO wake flag was set