drivers: hci: da1469x: Add driver for CMAC core on DA1469x

This adds HCI driver which enables communication with CMAC core on
Renesas SmartBond DA1469x series. The CMAC core is running an Apache
NimBLE controller binary and uses shared memory for communcation via
mailboxes.

Signed-off-by: Andrzej Kaczmarek <andrzej.kaczmarek@codecoup.pl>