spl: nand: support loading i.MX container format file

spl: nand: support loading i.MX container format file

i.MX8 only support AHAB secure boot with Container format image,
we could not use FIT to support secure boot, so introduce container
support to let SPL could load container images.

Cc: Simon Goldschmidt <[email protected]>
Cc: Tien Fong Chee <[email protected]>
Cc: York Sun <[email protected]>
Cc: Marek Vasut <[email protected]>
Cc: Alex Kiernan <[email protected]>
Cc: Simon Glass <[email protected]>
Cc: Philipp Tomsich <[email protected]>
Cc: Kever Yang <[email protected]>
Cc: Heiko Schocher <[email protected]>
Signed-off-by: Peng Fan <[email protected]>