Makefile.inc: Explicitly delete coreboot.pre

coreboot.pre doesn't follow the standard Make conventions. It gets
modified by multiple rules, and thus we can't compute the dependencies
correctly. This means we need to manually delete it before starting the
dependency calculations.

i.e., Building firmware with the seabios payload now works correctly.

Fixes: dd6efce934f ("Makefile: Add .SECONDARY")
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: If5fa3f0b8d314369a044658e452bd75bc7709397
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62922
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>
diff --git a/Makefile.inc b/Makefile.inc
index 929c236..377ddff 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -1116,6 +1116,10 @@
 TS_OPTIONS := -j $(CONFIG_INTEL_TOP_SWAP_BOOTBLOCK_SIZE)
 endif
 
+# coreboot.pre doesn't follow the standard Make conventions. It gets modified
+# by multiple rules, and thus we can't compute the dependencies correctly.
+$(shell rm -f $(obj)/coreboot.pre)
+
 ifneq ($(CONFIG_UPDATE_IMAGE),y)
 $(obj)/coreboot.pre: $(objcbfs)/bootblock.bin $$(prebuilt-files) $(CBFSTOOL) $(obj)/fmap.fmap $(obj)/fmap.desc
 	$(CBFSTOOL) $@.tmp create -M $(obj)/fmap.fmap -r $(shell cat $(obj)/fmap.desc)