Documentation: cpufreq: delete duplicate description of sysfs interface 'scaling_driver'

The file 'Documentation/cpu-freq/user-guide.txt' has duplicate
description of sysfs interface 'scaling_driver'.

[first]
scaling_driver :                this file shows what cpufreq driver is
				used to set the frequency on this CPU

[second]
scaling_driver :                Hardware driver for cpufreq.

Although this does not affect anything, I think we should only have
one. so delete the second one because the first one is described in
more detail.
Signed-off-by: Wang Long <long.wanglong@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Documentation/cpu-freq/user-guide.txt

@@ -196,8 +196,6 @@ affected_cpus :			List of Online CPUs that require software
 related_cpus :			List of Online + Offline CPUs that need software
 				coordination of frequency.
 
-scaling_driver :		Hardware driver for cpufreq.
-
 scaling_cur_freq :		Current frequency of the CPU as determined by
 				the governor and cpufreq core, in KHz. This is
 				the frequency the kernel thinks the CPU runs