MAINTAINERS: update for intel P-state driver

Add Srinivas Pandruvada and Len Brown as maintainers and remove
Kristen Carlson Accardi from the list of maintainers.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

MAINTAINERS

@@ -5405,7 +5405,8 @@ S:	Supported
 F:	drivers/idle/intel_idle.c
 
 INTEL PSTATE DRIVER
-M:	Kristen Carlson Accardi <kristen@linux.intel.com>
+M:	Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
+M:	Len Brown <lenb@kernel.org>
 L:	linux-pm@vger.kernel.org
 S:	Supported
 F:	drivers/cpufreq/intel_pstate.c