drm/nouveau/secboot/acr: fix memory leak

[ Upstream commit 74a07c0a59fa372b069d879971ba4d9e341979cf ]

In case memory resources for *bl_desc* were allocated, release
them before return.

Addresses-Coverity-ID: 1472021 ("Resource leak")
Fixes: 0d466901 ("drm/nouveau/secboot/acr: Remove VLA usage")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>