build: Fix import of gcc dependency files.

Make sure dependency file import works with new hw/ and fw/
sub-directories.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
diff --git a/Makefile b/Makefile
index 83820fe..70ba8d9 100644
--- a/Makefile
+++ b/Makefile
@@ -253,4 +253,4 @@
 $(OUT) $(addprefix $(OUT), $(DIRS)):
 	$(Q)mkdir $@
 
--include $(OUT)*.d
+-include $(patsubst %,$(OUT)%/*.d,$(DIRS))