Revert "PM / devfreq: Modify the device name as devfreq(X) for sysfs"

commit 66d0e797 upstream.

This reverts commit 4585fbcb

.

The name changing as devfreq(X) breaks some user space applications,
such as Android HAL from Unisoc and Hikey [1].
The device name will be changed unexpectly after every boot depending
on module init sequence. It will make trouble to setup some system
configuration like selinux for Android.

So we'd like to revert it back to old naming rule before any better
way being found.

[1] https://lkml.org/lkml/2018/5/8/1042

Cc: John Stultz <john.stultz@linaro.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable@vger.kernel.org
Signed-off-by: Orson Zhai <orson.unisoc@gmail.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>