simplify clobber behavior with out-of-tree builds

The targets/prerequisites are the same here; the rules only differ in
the recipes.  So move the if logic protection to the recipe part so we
can keep the rest the same.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

Makefile

diff --git a/Makefile b/Makefile
index 0707036..869755a 100644
--- a/Makefile
+++ b/Makefile
@@ -1105,12 +1105,9 @@
 	@[ ! -d $(obj)onenand_ipl ] || find $(obj)onenand_ipl -name "*" -type l -print | xargs rm -f
 	@[ ! -d $(obj)mmc_spl ] || find $(obj)mmc_spl -name "*" -type l -print | xargs rm -f
 
-ifeq ($(OBJTREE),$(SRCTREE))
 mrproper \
 distclean:	clobber unconfig
-else
-mrproper \
-distclean:	clobber unconfig
+ifneq ($(OBJTREE),$(SRCTREE))
 	rm -rf $(obj)*
 endif