Bluetooth: AMP: Use HCI cmd to Read Loc AMP Assoc

When receiving A2MP Get AMP Assoc Request execute Read Local AMP Assoc
HCI command to AMP controller. If the AMP Assoc data is larger than it
can fit to HCI event only fragment is read. When all fragments are read
send A2MP Get AMP Assoc Response.

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>