Merge branch 'sh_eth-implement-simple-RX-checksum-offload'

Sergei Shtylyov says:

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sh_eth: implement simple RX checksum offload

Here's a set of 7 patches against DaveM's 'net-next.git' repo. I'm implemeting
the simple RX checksum offload (like was done for the 'ravb' driver by Simon
Horman); it has been only tested on the R8A7740 and R8A77980 SoCs, the other
SoCs should just work (according to their manuals)...
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Signed-off-by: David S. Miller <davem@davemloft.net>