drivers/net/cs89x0.c: Avoid using magic number in set_dma_mode

The constant DMA_RX_MODE is defined to be 0x14 in the local include file
cs89x0.h.  Since a constant with the same name is used elsewhere with
set_dma_mode, it seems likely that this constant could be used here.

The semantic match that finds this problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@ expression E1; identifier I; constant int C; @@
(
set_dma_mode(E1,I,...)
|
*set_dma_mode(E1,C,...)
)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: David S. Miller <davem@davemloft.net>