scripts/setlocalversion: remove workaround for old make-kpkg

This reverts commit b052ce4c ("kbuild: fix false positive -dirty
tag caused by make-kpkg").

If I understand correctly, this problem occurred in very old versions
of make-kpkg. When I tried a newer version, make-kpkg did not touch
scripts/package/Makefile.

Anyway, Debian uses 'make deb-pkg' instead of make-kpkg these days.

Debian handbook [1] mentions it as "the good old days":

 "CULTURE The good old days of kernel-package

  Before the Linux build system gained the ability to build proper
  Debian packages, the recommended way to build such packages was to
  use make-kpkg from the kernel-package package."

[1]: https://debian-handbook.info/browse/stable/sect.kernel-compilation.html



Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Nico Schottelius <nico-linuxsetlocalversion@schottelius.org>