d/control.in: remove linux-image-librem5 package on next branch
since commit 36862e14 ("kbuild: deb-pkg: use dh_listpackages to know enabled packages") debian/control is the description of what to build basically.
keep it simple and simply remove this binary package in "next" kernel trees that release linux-next-librem5 source packages.
Since we generate d/control, this commit can simply be reverted for the linux-librem5 source package releases.
this should fix #479 (closed)