package/kmod: modinfo support of signature details

Add conditional support to allow the module tools to use openssl
on target to inspect the signature of signed modules. If openssl
is not enabled the modinfo will show a hash algo as unknown.

Signed-off-by: Matthew Weber <matthew.weber@rockwellcollins.com>
Tested-by: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>