Re-run the git-describe if it fails at first try.

Old rev (1.6.6, in my case) git-describe doesn't take the --dirty and says error.
Remove the --dirty at second try.

Change-Id: Id6c6f9889ab20fb7c2b238f8c0bbe20134757369
Signed-off-by: Zheng Bao <zheng.bao@amd.com>
Signed-off-by: zbao <fishbaozi@gmail.com>
Reviewed-on: http://review.coreboot.org/1261
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
1 file changed