tools/power turbostat: support "--hide C1" etc.

Originally, the only way to hide the sysfs C-state statistics columns
was with "--hide sysfs".  This was because we process "--hide" before
we probe for those columns.

hack --hide to remember deferred hide requests, and apply
them when sysfs is probed.

"--hide sysfs" is still available as short-hand to refer to
the entire group of counters.

The down-side of this change is that we no longer error check for
bogus --hide column names.  But the user will quickly figure that
out if a column they mean to hide is still there...

Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/tools/power/x86/turbostat/turbostat.8 b/tools/power/x86/turbostat/turbostat.8
index 5189d9d..fedca32 100644
--- a/tools/power/x86/turbostat/turbostat.8
+++ b/tools/power/x86/turbostat/turbostat.8
@@ -114,7 +114,7 @@
 .PP
 When you are not interested in all that information, and there are several ways to see only what you want.  First the "--quiet" option will skip the configuration information, and turbostat will show only the counter columns.  Second, you can reduce the columns with the "--hide" and "--show" options.  If you use the "--show" option, then turbostat will show only the columns you list.  If you use the "--hide" option, turbostat will show all columns, except the ones you list.
 .PP
-To find out what columns are available for --show and --hide, the "--list" option is available.  Note, however, there is an exception.  The C-state columns collected from sysfs "C1,C2,C3,C1%,C2%,C3%" are not built-in counters, but are discovered after --show and --hide are processed.  You can use the special counter name "sysfs" to refer to all of them at the same time.
+To find out what columns are available for --show and --hide, the "--list" option is available.  For convenience, the special strings "sysfs" can be used to refer to all of the sysfs C-state counters at once:
 .nf
 sudo ./turbostat --show sysfs --quiet sleep 10
 10.003837 sec