net: Fix typos and whitespace.

Fix typos.  Capitalize CPU, NAPI, RCU consistently.  Align structure
indentation.  No functional change intended; only comment and whitespace
changes.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>