cmd: blob: Instantiate RNG before running CMD_BLOB

U-Boot can instantiate CAAM RNG if needed by crypto operations.
Call sec_init() prior running a blob operation to ensure
RNG is correctly instantiated.

Make sure CAAM clock is enabled and check if a job ring is
available for that operation.

Signed-off-by: Breno Lima <breno.lima@nxp.com>
Reviewed-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>