kbuild: deb-pkg: use more debhelper commands in builddeb

Commit 36862e14 ("kbuild: deb-pkg: use dh_listpackages to know
enabled packages") started to require the debhelper tool suite.

Use more dh_* commands in create_package():

 - dh_installdocs to install copyright
 - dh_installchangelogs to install changelog
 - dh_compress to compress changelog
 - dh_fixperms to replace the raw chmod command
 - dh_gencontrol to replace the raw dpkg-gencontrol command
 - dh_md5sums to record the md5sum of included files
 - dh_builddeb to replace the raw dpkg-deb command

Set DEB_RULES_REQUIRES_ROOT to 'no' in case debian/rules is executed
directly.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <n.schier@avm.de>