sh_eth: factor out sh_eth_emac_interrupt()

The E-MAC interrupt (EESR.ECI) is not always caused  by an error condition,
so  it really shouldn't be handled by sh_eth_error(). Factor out the E-MAC
interrupt handler, sh_eth_emac_interrupt(),  removing the ECI bit from the
EESR's values throughout the driver...

Update Cogent Embedded's copyright and clean up the whitespace in Renesas'
copyright, while at it...

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