kernel-yocto: inhibit BSP description warnings for custom linux-yocto kernels
We don't require that a yocto custom kernel + defconfig have a full BSP
description (but of course it would be better if they did). Since this
isn't a requirement, we shouldn't alarm users by generating a BSP
description warning.
To implement this, we add a bsp audit level flag (like the one that
exists for kconfig audits), and only set it to activate in the versioned
linux-yocto recipes.
[YOCTO: #7370]
Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
