configs: imx8m: Prepare imx8m-venice boards for HAB support

In order to enable HAB, FSL_CAAM, ARCH_MISC_INIT and
SPL_CRYPTO should be enabled in Kconfig like other i.MX8M
boards.

This also needs to occur in the SPL so enable CONFIG_SPL_BOARD_INIT and
add a void spl_board_init function which calls arch_misc_init to probe
the CAAM driver.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>