sh_eth: remove sh_eth_plat_data::edmac_endian

Since the commit 888cc8c2 ("sh_eth: remove EDMAC_BIG_ENDIAN") (geez,
I didn't realize that was 2 years ago!) the initializers in the SuperH
platform code for the 'sh_eth_plat_data::edmac_endian' stopped to matter,
so we can remove that field for good (not sure if  it  was ever useful --
SH7786 Ether has been reported  to have the same EDMAC descriptor/register
endiannes as configured for the SuperH CPU)...

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>