Bluetooth: hci_uart: Add support for vendor detection flag

This adds a new HCI_UART_VND_DETECT flag to allow automatic vendor
detection. This allows to enable known vendor commands (for example
for setting the public device address) when using a standard H:4
UART protocol or when running in virtual machines.

When this new flag is configured and no vendor specific setup
routine is provided, then the local version information are read
and the provided manufacturer information can be evaluated to
configure extra vendor callbacks.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>