monitor: Fix using uuid128_to_str

This function always return "Unknown" regardless of the input, instead
uuidstr_to_str shall be used for UUID 128 bit format since it can return
proper friendly names:

> ACL Data RX: Handle 3585 flags 0x02 dlen 26
      ATT: Read By Group Type Response (0x11) len 21
        Attribute data length: 20
        Attribute group list: 1 entry
        Handle range: 0x0001-0x0015
        UUID: Eddystone Configuration Service (a3c87500-8ed3-4bdf-8a39-a01bebede295)
1 file changed