sfc: Add/remove blank lines to taste

Remove trailing blank lines in several files.
Use only one blank line between functions.
Add a blank line as a separator in a few places.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Shradha Shah <sshah@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>