This forces a rebuild of the wolfssl package when the
libwolfssl-benchmark OpenWrt package gets activated or deactivated.
Without this change the wolfssl build will fail when it compiled without
libwolfssl-benchmark before and it gets activated for the next build.
Fixes: 18fd12edb8 ("wolfssl: add benchmark utility")
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>