Remove patches that were upstreamed or are not relevant anymore. Replace
the xauth patch with the rebased version from upstream.
Add the dropbear-disable-weak-ciphers.patch from upstream OE.
Add "--disable-harden" just like in the upstream recipe, as OE's
hardening flags cause the textrel QA warning otherwise.
Related: https://git.openembedded.org/openembedded-core/tree/meta/recipes-core/dropbear/
Related: SYS#6402
Change-Id: I431934b0558350931bb9571b0fa6efff8ba45387