Prevent the bt_rand function from being called before bt_enable.
Depending on the implementation of bt_rand this function cannot
be called before bluetooth has been initialized. With host supplied
crypto functions the HCI LE rand command is used for example.
The use case for calling bt_id_create before bt_enable is meant for
when the application has storage for the identity instead of the stack.
So we add the requirement that the application has to have storage
for the identity resolving key (IRK) in addition when the local
device is privacy-enabled.
Signed-off-by: Joakim Andersson <joakim.andersson@nordicsemi.no>
8a55e04e23