OCOTP: Update OCOTP driver to support i.MX6SLL

Add the i.MX6SLL support to OCOTP driver.

The i.MX6SLL reuses the i.MX6ULL fuse, bank 7 and bank8 have 4 words
each, and there is a hole between bank 5 and bank 6.

Signed-off-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>