Kernel recategorization

In our latest team meeting we decided to recategorize our kernels in main. We have en entire folder for device specific packages but for some reasons almost all our "close-to mainline" kernels where in main instead.

During the last CVE "fire drill" we noticed that a large amount of time was taken up by figuring out what kernels are actually used by our supported devices, and a large amount in main weren't actually used by them. Thus we're now moving kernels to where they make sense: to the category they're being used in.

Of course a kernel can be used by a device in both community and testing for example, but in those cases the kernel will move to the "best" or "highest" category it's used in.