net: fec: no need to test for the return type of of_property_read_u32

in case of error no need to set num_tx and num_rx = 1, because in case of error
these variables will remain unchanged by of_property_read_u32 ie 1 only

Signed-off-by: Saurabh Sengar <saurabh.truth@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>