microblaze: Fix build with make 3.82

When running make headers_install_all on x86_64 and make 3.82 I hit this:

arch/microblaze/Makefile:80: *** mixed implicit and normal rules.  Stop.
make: *** [headers_install_all] Error 2

So split the rules to satisfy make 3.82.
Signed-off-by: Thomas Backlund <tmb@mandriva.org>
Cc: Stable <stable@kernel.org>
Signed-off-by: Michal Simek <monstr@monstr.eu>

arch/microblaze/Makefile

@@ -69,12 +69,16 @@ export MMU DTB
 
 all: linux.bin
 
-BOOT_TARGETS = linux.bin linux.bin.gz simpleImage.%
+# With make 3.82 we cannot mix normal and wildcard targets
+BOOT_TARGETS1 = linux.bin linux.bin.gz
+BOOT_TARGETS2 = simpleImage.%
 
 archclean:
 	$(Q)$(MAKE) $(clean)=$(boot)
 
-$(BOOT_TARGETS): vmlinux
+$(BOOT_TARGETS1): vmlinux
+	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
+$(BOOT_TARGETS2): vmlinux
 	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
 
 define archhelp