Revert extra modifications to source tree

This reverts modifications to the Linux kernel stable source tree
(git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git)
except those which implement CSI Tool support. The CSI Tool README
is renamed to avoid conflicting with the Linux kernel release notes
(but it will still appear as the markdown in Github).

This makes it easier to merge this tree with distribution-specific
kernel changes, or to rebase the CSI Tool support onto other kernel
versions.
csitool: Use connector ID from out-of-tree range

This allows the iwlwifi module to be rebuilt for an existing kernel
and installed in the module 'updates' directory, without needing to
rebuild and install the entire kernel.
csitool: End error message with newline