CP-6002 minimize Linux kernel build to only include necessary kernel modules

[prakashsurya]

No description provided.

[prakashsurya]

In my preliminary testing, this change on its own, shouldn't have any functional impact to the product.. but, it will allow us to make changes to the kernel repositories, such that we can tweak the resultant kernel config file that is used during the kernel build process.

I suggest we start with this change in isolation, such that it'll be easier to build, test, and verify any subsequent kernel changes.

[prakashsurya]

git-ab-pre-push is here (with kernel build)

[sdimitro]

^ For Seb's feedback above:
Some of these steps I copy pasted them in the script straight from the command line as I was doing different iterations outside of linux-pkg, so I think it'd make sense to check whether they are needed.

[prakashsurya]

yea, seems like all we need is that one line to update the configs.. so that's what I'll go with.. I'll wait for the build to verify, but it's looking good so far.