sh_eth: enable RX descriptor word 0 shift on SH7734

The RX descriptor word 0 on SH7734 has the RFS[9:0] field in bits 16-25
(bits  0-15 usually used for that are occupied by the packet checksum).
Thus  we need to set the 'shift_rd0'  field in the SH7734 SoC data...

Fixes: f0e81fec

 ("net: sh_eth: Add support SH7734")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>