kbuild: Add make tarxz-pkg build option

Signed-off-by: Zdenek Kaspar <zkaspar82@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
diff --git a/scripts/package/Makefile b/scripts/package/Makefile
index d0b931b..a834b93 100644
--- a/scripts/package/Makefile
+++ b/scripts/package/Makefile
@@ -127,7 +127,8 @@
 $(if $(findstring tar-src,$@),,                                     \
 $(if $(findstring bz2,$@),bzip2,                                    \
 $(if $(findstring gz,$@),gzip,                                      \
-$(error unknown target $@)))                                       \
+$(if $(findstring xz,$@),xz,                                        \
+$(error unknown target $@))))                                       \
 	-f -9 $(perf-tar).tar)
 
 perf-%pkg: FORCE
@@ -142,7 +143,9 @@
 	@echo '  tar-pkg             - Build the kernel as an uncompressed tarball'
 	@echo '  targz-pkg           - Build the kernel as a gzip compressed tarball'
 	@echo '  tarbz2-pkg          - Build the kernel as a bzip2 compressed tarball'
+	@echo '  tarxz-pkg           - Build the kernel as a xz compressed tarball'
 	@echo '  perf-tar-src-pkg    - Build $(perf-tar).tar source tarball'
 	@echo '  perf-targz-src-pkg  - Build $(perf-tar).tar.gz source tarball'
 	@echo '  perf-tarbz2-src-pkg - Build $(perf-tar).tar.bz2 source tarball'
+	@echo '  perf-tarxz-src-pkg  - Build $(perf-tar).tar.xz source tarball'