xtensa: clean up boot make rules

- remove duplicate rules for binary and packed image
- use predefined macros for ld/objcopy/gzip
- remove build-id section from bootable elf image

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
diff --git a/arch/xtensa/boot/Makefile b/arch/xtensa/boot/Makefile
index 4018f89..4453859 100644
--- a/arch/xtensa/boot/Makefile
+++ b/arch/xtensa/boot/Makefile
@@ -31,3 +31,13 @@
 	      $(addprefix $(obj)/,$(host-progs))
 	$(Q)$(MAKE) $(build)=$(obj)/$@ $(MAKECMDGOALS)
 
+OBJCOPYFLAGS = --strip-all -R .comment -R .note.gnu.build-id -O binary
+
+vmlinux.bin: vmlinux FORCE
+	$(call if_changed,objcopy)
+
+vmlinux.bin.gz: vmlinux.bin FORCE
+	$(call if_changed,gzip)
+
+boot-elf: vmlinux.bin
+boot-redboot: vmlinux.bin.gz