sfc: Fix some incorrect or redundant comments

In particular, the comment about EVQ_RPTR_REG is based on inconsistent
preliminary hardware documentation, though the following code was
fixed long before release.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
4 files changed