cpufreq: Fix scaling_{available,boost}_frequencies_show() comments

The function names in the comment blocks for the functions
scaling_available_frequencies_show() and
scaling_boost_frequencies_show() do not match the actual names.

Fixes: 6f19efc0 ("cpufreq: Add boost frequency support in core")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>