Add WLAN card support

Add WLAN card support

This is loosely based on the contents of the tar file provided with
the WLAN cards (AGL_Refhw_sample_software_KK_20210225.tar.gz) with
updates for BSP v4.7.0 and other fixes.

Changes:
- Kernel patches and configuration update to enable the TI WL1837
  module.  As opposed to the original changes from Panasonic or the
  Kingfisher support, the HCI LL driver is used instead of the older
  ti-st + btwilink combination, since the the latter are deprecated
  and are removed in kernel 5.5.
- As part of the above the sound configuration in the devicetree has
  been reworked to support the WL1837 BT audio.  This includes
  dropping the HDMI1 audio configuration from the original Salvator-X
  devicetree, as it conflicts with the SSI used for the ak4613 in the
  reference hardware.
- Recipes added for wlconf (from meta-ti) and ti-bt-firmware (loosely
  derived from the meta-rcar-gen3-adas version).  The TI-TFL license
  used by ti-bt-firmware has been added in a top-level "licenses"
  directory and that added to LICENSE_PATH in layer.conf to satisfy
  the license packaging QA checking.

Bug-AGL: SPEC-4071

Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: Ib17fc01331efe0f49a90f7a8b223ec88b33b44f7