Revert "xfrm: interface: use DEV_STATS_INC()"

This reverts commit d4d40dc7 which is
commit f7c4e3e5d4f6609b4725a97451948ca2e425379a upstream.

It breaks the build due to a previous abi-breaking change being dropped
from the tree.  If this is needed in the future, it can come back in an
abi-safe way.

Change-Id: I5fab397dfff850ab54026e62930bec9b0655cf62
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>