ADS5121 Add IC Ident Module (IIM) support

IIM (IC Identification Module) is the fusebox for the mpc5121.
Use #define CONFIG_IIM to turn on the clock for this module
use #define CONFIG_CMD_FUSE to add fusebox commands.
Fusebox commands include the ability to read
the status, read the register cache, override the register cache,
program the fuses and sense them.

Signed-off-by: Martha Marx <mmarx@silicontkx.com>
Signed-off-by: John Rigby <jrigby@freescale.com>