Bluetooth: Fix identity creation through vendor HCI

The code creating identities from the Read_Static_Addresses vendor
command was failing to create matching IRKs, resulting in an
all-zeroes IRK to be used. Fix this by using the existing id_create()
function which takes care of generaing an IRK when necessary.

Fixes #10003

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>