netfilter: fix ebtables compat support

commit 255d0dc3 (netfilter: x_table: speedup compat operations)
made ebtables not working anymore.

1) xt_compat_calc_jump() is not an exact match lookup
2) compat_table_info() has a typo in xt_compat_init_offsets() call
3) compat_do_replace() misses a xt_compat_init_offsets() call

Reported-by: dann frazier <dannf@dannf.org>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>