The GW74xx supports an on-board Laird Connectivity Sterling LWB5+ module
which uses a Cypress CYW4373W chip to provide 1x1 802.11 a/b/g/n/ac +
Bluetooth 5.2.

Add the proper device-tree nodes for it.
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>