sf: Add SPI protection mechanism from the kernel

sf: Add SPI protection mechanism from the kernel

Add the SPI NOR protection mechanism from the kernel.

This code is based on the work from
Brian Norris <[email protected]>
Here is the commit details:
"mtd: spi-nor: refactor block protection functions"
(sha1: 62593cf40b23b523b9fc9334ca61ba6c595ebb09)

Signed-off-by: Fabio Estevam <[email protected]>
Signed-off-by: Jagan Teki <[email protected]>
Reviewed-by: Tom Rini <[email protected]>
Reviewed-by: Heiko Schocher <[email protected]>
Reviewed-by: Jagan Teki <[email protected]>
Signed-off-by: Fabio Estevam <[email protected]>