sanitycheck: filter out the prebuilt.elf introduced by Makefile cleanup

commit 018b831a369d6b3435bd1d6ecfe7b77915dd0acf keeps another elf file in the
outdir which confused the sanitycheck script.

Change-Id: I87a9bcee6afe6526ecc24f1f5d9cf38101247ce2
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
1 file changed