r8152: remove generic_ocp_read before writing

For ocp_write_word() and ocp_write_byte(), there is a generic_ocp_read()
which is used to read the whole 4 byte data, keep the unchanged bytes,
and modify the expected bytes. However, the "byen" could be used to
determine which bytes of the 4 bytes to write, so the action could be
removed.

Signed-off-by: Hayes Wang <hayeswang@realtek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>