sf: Add lock ops for SST SPI NOR flash

SST SPI NOR flash has the same locking programming bits
as ST Micro - added support for it.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
[Minor change on commit message]
Signed-off-by: Jagan Teki <jteki@openedev.com>
Reviewed-by: Jagan Teki <jteki@openedev.com>
3 files changed