linux-yocto/5.4: remove recipes

We have 5.10 and 5.13 as the active recipes in the release/development
branches, so we remove 5.4.

This leaves us with the standard three versions for release (5.10,
5.13 and -dev).

5.4 will continue to be updated in stable/supported releases.

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>