MLK-17082-01 imx: add optee support for imx6sll

MLK-17082-01 imx: add optee support for imx6sll

Add different defconfig for optee;
Enable the TZASC support;
Add env config for tee support.

Signed-off-by: Bai Ping <ping.bai@nxp.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
(cherry picked from commit 1f86ee60e72bb56af69a4128e8234e08c9bb1f59)
(cherry picked from commit 819b988f3f1a8a207a380b09b4c71374b4b3ae0b)
(cherry picked from commit 7d816e96f304a2a899efb675fda153ebe84775d2)
(cherry picked from commit 53889189eca457cc915d2270c0034f225d9719ed)
(cherry picked from commit 2300844b9ce5992fc835605752fbbcee5be98a6b)
(cherry picked from commit 18fdda30a9da0f3f679bd4417d62bc0c6bd86d9f)