Bluetooth: Make BT_HCIUART_RTL configuration option depend on ACPI

Bluetooth: Make BT_HCIUART_RTL configuration option depend on ACPI

At the moment we only support ACPI enumeration for serial port attached
RTL bluetooth controllers.

This commit adds a dependency on ACPI to the BT_HCIUART_RTL configuration
option, fixing the following warning when ACPI is not enabled:

drivers/bluetooth/hci_h5.c:920:22: warning: 'rtl_vnd' defined but not used

Cc: Arnd Bergmann <arnd@arndb.de>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>