MIPS: loongson32: Drop obsolete cpufreq platform device

The obsolete cpufreq driver was removed, drop the platform device
and data accordingly.

Link: https://lore.kernel.org/all/20230112135342.3927338-1-keguang.zhang@gmail.com


Signed-off-by: Keguang Zhang <keguang.zhang@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>