mtd: spi-nor: Update lock/unlock support

Update the block protect bits and their calculation for Spansion and Micron.
Add support for lock/unlock in parallel and stacked configurations.

Signed-off-by: Harini Katakam <harinik@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>