board: nxp: imx9{4, 5, 52}_evk: Add qb save option in SPL

board: nxp: imx9{4, 5, 52}_evk: Add qb save option in SPL

Call qb save automatically in the board-specific
spl_board_init(), if SPL_IMX_QB option is enabled.
This makes sure qb_save is called before any image
loading is done by the SPL. This option is also
suitable for the case where U-Boot proper is
missing (Falcon mode).

qb save refers to saving DDR training data to NVM,
so that OEI runs Quickboot flow on next reboot,
skipping full training and achieveing a lower boot
time.

Signed-off-by: Simona Toaca <simona.toaca@nxp.com>