Revert "nfp: abm: fix memory leak in nfp_abm_u32_knode_replace"

Revert "nfp: abm: fix memory leak in nfp_abm_u32_knode_replace"

[ Upstream commit 1d1997db870f4058676439ef7014390ba9e24eb2 ]

This reverts commit 78beef629fd9 ("nfp: abm: fix memory leak in
nfp_abm_u32_knode_replace").

The quoted commit does not fix anything and resulted in a bogus
CVE-2019-19076.

If match is NULL then it is known there is no matching entry in
list, hence, calling nfp_abm_u32_knode_delete() is pointless.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: John Hurley <john.hurley@netronome.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>