Empty list check to stop Bluetooth stack crash in btif_rc

Remote devices sometimes poorly send 0 capabilities response when
connecting AVRCP. The stack currently crashes in response to this. We
should not crash and continue. Typically the remote device will send
proper packets in the future and continue to work properly.

Bug: 70140873
Test: Faked 0 capabilities, made stack crash. Added fix, stack stopped
crashing. Verified Bluetooth streaming working.

Change-Id: Id51f0593bc0ddcd3c3085b0d1b1fae136baecceb