net/r8169: Update the function of parsing firmware

Update rtl_phy_write_fw function. The new function could
parse the complex firmware which is used by RTL8111E and later.
The new firmware may read data and do some operations, not just
do writing only.

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