payloads/coreinfo: Fix `make clean`

After `make clean` a new build should not be based on stale artifacts.
Hence we have to remove them.

Change-Id: I18292c674986078d991668124193b6aa31234d47
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44179
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

payloads/coreinfo/Makefile

@@ -128,10 +128,9 @@ include $(srck)/Makefile
 else
 
 clean:
-	rm -rf build/*.elf build/*.o .xcompile
+	rm -rf build lpbuild .xcompile
 
 distclean: clean
-	rm -rf build lpbuild
 	rm -f .config* lp.config*
 
 .PHONY: clean distclean