Doc: cpufreq: Fix typo and outdated line

'sampling_rate_max' was removed with commit ef598549 ("[...] Remove
deprecated sysfs file sampling_rate_max"), so its line can be dropped
from governors.txt. And 'show_sampling_rate_min' is a typo: the sysfs
file is called 'sampling_rate_min'.
Signed-off-by: NPaul Bolle <pebolle@tiscali.nl>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Documentation/cpu-freq/governors.txt

@@ -127,7 +127,7 @@ in the bash (as said, 1000 is default), do:
 echo `$(($(cat cpuinfo_transition_latency) * 750 / 1000)) \
     >ondemand/sampling_rate
 
-show_sampling_rate_min:
+sampling_rate_min:
 The sampling rate is limited by the HW transition latency:
 transition_latency * 100
 Or by kernel restrictions:
@@ -140,8 +140,6 @@ HZ=100:  min=200000us (200ms)
 The highest value of kernel and HW latency restrictions is shown and
 used as the minimum sampling rate.
 
-show_sampling_rate_max: THIS INTERFACE IS DEPRECATED, DON'T USE IT.
-
 up_threshold: defines what the average CPU usage between the samplings
 of 'sampling_rate' needs to be for the kernel to make a decision on
 whether it should increase the frequency.  For example when it is set