powercap: intel_rapl: Use sysfs_emit() in cpumask_show()

cpumask_show() is a sysfs show callback, so use sysfs_emit() and
cpumask_pr_args() to emit the mask in it.

This prepares for removing cpumap_print_to_pagebuf().

Signed-off-by: Yury Norov <ynorov@nvidia.com>
[ rjw: Subject and changelog tweaks ]
Link: https://patch.msgid.link/20260528183625.870813-15-ynorov@nvidia.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/powercap/intel_rapl_common.c

@@ -1441,7 +1441,7 @@ static ssize_t cpumask_show(struct device *dev,
 	}
 	cpus_read_unlock();
 
-	ret = cpumap_print_to_pagebuf(true, buf, cpu_mask);
+	ret = sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(cpu_mask));
 
 	free_cpumask_var(cpu_mask);