Setting of flash_sector::is_erased in flash erase and mass erase
is popular folklore. Make clear it is useless.
Change-Id: Ide397eb6d24fc8fa38931e6c8a0693d39668a5d2
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: http://openocd.zylin.com/4768
Tested-by: jenkins
Reviewed-by: Christopher Head <chead@zaber.com>