kbuild: arch/i386/boot*, use kbuild syntax when descending into compressed

Use proper kbuild syntax when descending into compressed.
The use of $(Q)$(MAKE) $(build)=... is the preferred method

arch/i386/boot/Makefile

@@ -58,8 +58,7 @@ $(obj)/setup $(obj)/bootsect: %: %.o FORCE
 	$(call if_changed,ld)
 
 $(obj)/compressed/vmlinux: FORCE
-	$(Q)$(MAKE) -f scripts/Makefile.build obj=$(obj)/compressed \
-					IMAGE_OFFSET=$(IMAGE_OFFSET) $@
+	$(Q)$(MAKE) $(build)=$(obj)/compressed IMAGE_OFFSET=$(IMAGE_OFFSET) $@
 
 # Set this if you want to pass append arguments to the zdisk/fdimage kernel
 FDARGS = 

arch/i386/boot98/Makefile

@@ -58,8 +58,7 @@ $(obj)/setup $(obj)/bootsect: %: %.o FORCE
 	$(call if_changed,ld)
 
 $(obj)/compressed/vmlinux: FORCE
-	$(Q)$(MAKE) -f scripts/Makefile.build obj=$(obj)/compressed \
-					IMAGE_OFFSET=$(IMAGE_OFFSET) $@
+	$(Q)$(MAKE) $(build)=$(obj)/compressed IMAGE_OFFSET=$(IMAGE_OFFSET) $@
 
 # Set this if you want to pass append arguments to the zdisk/fdimage kernel
 FDARGS =