r8152: support jumbo frame for RTL8153

The maximum jumbo frame size for RTL8153 is 9K bytes.
Change the max rx packet size to 9K.
Change the use of the shared fifo from 6K (default) to 12K for tx.

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