NFC: llcp: Use default MIU if none was specified on connect

If MIUX is not present in CONNECT or CC use default MIU value (128)
instead of one announced durring link setup.

This was affecting Bluetooth handover with Android 4.3+ NCI stack.

Signed-off-by: Szymon Janc <szymon.janc@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>