powerpc/platforms/83xx: Use of_device_get_match_data()

Use of_device_get_match_data() to simplify the code.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Minghao Chi (CGEL ZTE) <chi.minghao@zte.com.cn>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220225010737.2038781-1-chi.minghao@zte.com.cn