During the refactoring for the ksz8_dev_ops from ksz8795.c to
ksz_common.c, the ksz8_r_mib_cnt has been missed. So this patch adds the
missing one.

Fixes: 6ec23aaa ("net: dsa: microchip: move ksz_dev_ops to ksz_common.c")
Signed-off-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20220718061803.4939-1-arun.ramadoss@microchip.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>