sh_eth: rename sh_eth_cpu_data::hw_checksum

Commit 62e04b7e ("sh_eth: rename 'sh_eth_cpu_data::hw_crc'") renamed
the field to 'hw_checksum' for the Ether DMAC "intelligent checksum",
however some Ether MACs implement a simpler checksumming scheme, so that
name now seems misleading. Rename that field to 'csmr' as the "intelligent
checksum" is always controlled by the CSMR register.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: David S. Miller <davem@davemloft.net>