kbuild: deb-pkg: fix versioning for -rc releases

The version number with -rc should be considered older than the final
release.

For example, 6.14-rc1 should be older than 6.14, but to handle this
correctly (just like Debian kernel), "-rc" must be replace with "~rc".

  $ dpkg --compare-versions 6.14-rc1 lt 6.14
  $ echo $?
  1
  $ dpkg --compare-versions 6.14~rc1 lt 6.14
  $ echo $?
  0

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>