builddeb: clean generated package content

For each binary Debian package, a directory with the package name is
created in the debian directory. Correct the generated file matches in the
package's clean target, which were renamed without adjusting the target.

Fixes: 1694e94 ("builddeb: match temporary directory name to the package name")
Signed-off-by: Bastian Germann <bage@linutronix.de>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Author: Bastian Germann

scripts/package/mkdebian

@@ -236,7 +236,7 @@ binary-arch: build-arch
 	KBUILD_BUILD_VERSION=${revision} -f \$(srctree)/Makefile intdeb-pkg
 
 clean:
-	rm -rf debian/*tmp debian/files
+	rm -rf debian/files debian/linux-*
 	\$(MAKE) clean
 
 binary: binary-arch