cpupower-frequency-info.1: use the proper name of the --perf option

The cpupower-frequency-info(1) man page describes a '--perf' option.
Even though this form is accepted by the program, its proper name is
'--performance'.

cpufreq-info.c:
	{"performance", no_argument,	 NULL,	 'c'},

Signed-off-by: Roberto Ricci <io@r-ricci.it>
Link: https://lore.kernel.org/r/20260324223921.14317-3-io@r-ricci.it
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Author: r-ricci

tools/power/cpupower/man/cpupower-frequency-info.1

@@ -53,7 +53,7 @@ human\-readable output for the \-f, \-w, \-s and \-y parameters.
 \fB\-n\fR \fB\-\-no-rounding\fR
 Output frequencies and latencies without rounding off values.
 .TP  
-\fB\-c\fR \fB\-\-perf\fR
+\fB\-c\fR \fB\-\-performance\fR
 Get performances and frequencies capabilities of CPPC, by reading it from hardware (only available on the hardware with CPPC).
 .TP
 .SH "REMARKS"