AptX Voice: Check sysprop in addition to Flag

The codec has dependency on hardware. Using a sysprop will prevent wrong
usage of it

Bug: 308497929
Test: m Bluetooth | no-op test
Test: atest bt_host_test_bta | Cf aosp/2679780
Change-Id: I5c0c24b65cf16b1b91b4a553c7be2a08c2e079b9