Revert "xfrm: interface: use DEV_STATS_INC()"

This reverts commit 0cb7b894 which is
commit 0cb7b894 upstream.

It breaks the build as it depends on an abi-breaking commit that was
previously reverted.  If this is needed in the future, it can come back
in an abi-safe way.

Bug: 161946584
Change-Id: Ib8c4c34c281fdbe75397a9508155b04ab1e63c8d
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>