sh_eth: rename 'sh_eth_cpu_data::hw_crc'

The 'struct sh_eth_cpu_data' field indicating the "intelligent checksum"
support was misnamed 'hw_crc' -- rename it to 'hw_checksum'.

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