Add prefix coreboot_ to let make clean find it and delete it.
Change-Id: Ieba9c0e7ca3d2afec311d64159b22746ba5825c4
Signed-off-by: Zheng Bao <zheng.bao@amd.com>
Signed-off-by: zbao <fishbaozi@gmail.com>
Reviewed-on: http://review.coreboot.org/2029
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>