px5g-wolfssl: Fix certificate signature

Certificate signature algorithm was being set after call to
`wc_MakeCert`, resulting in a mismatch between specified signature in
certificate and the actual signature type.

Signed-off-by: Jeffrey Elms <jeff@wolfssl.com>
[fix commit subject, use COMMITCOUNT]
Signed-off-by: Paul Spooren <mail@aparcar.org>