Using Linux firmware to pull in Qualcomm 6234 bluetooth drivers.

Using github/qca to pull in Qualcomm 6234 wifi drivers.
Fixed symbolic links for rigtools.
Updated u-boot to latest commit.
Removed Qualcomm 6234 wifi and bluetooth drivers from firmware-vesta.
Removed unneeded recipes from core-image-minimal.
Added new firmware recipes to core-image-minimal.
Added new firmware recipes to engr-test-image.