cpufreq: powerpc: add missing MODULE_DESCRIPTION() macros

With ARCH=powerpc, make allmodconfig && make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/cpufreq/ppc-cbe-cpufreq.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/cpufreq/powernv-cpufreq.o

Add the missing invocation of the MODULE_DESCRIPTION() macro to all
files which have a MODULE_LICENSE().

This includes three additional files which, although they did not
produce a warning with the powerpc allmodconfig configuration, may
cause this warning with specific options enabled in the kernel
configuration.

Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://patch.msgid.link/20240722-md-powerpc-drivers-cpufreq-v2-1-bb84d715eb3d@quicinc.com


Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>