cpufreq: remove cris specific drivers

The cris architecture is getting removed, including the artpec3
and etraxfs SoCs, so these cpufreq drivers are now unused.

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>