MLK-17897: mx7ulp: Move CONFIG_SECURE_BOOT option to Kconfig

MLK-17897: mx7ulp: Move CONFIG_SECURE_BOOT option to Kconfig

Since commit 6e1f4d2652e79 ("arm: imx-common: add SECURE_BOOT option
to Kconfig") it's preferable to select CONFIG_SECURE_BOOT via Kconfig.

Add ARCH_MX7ULP as a CONFIG_SECURE_BOOT dependency, do not select
CONFIG_FSL_CAAM since CAAM is not implemented for i.MX7ULP yet.

Signed-off-by: Breno Lima <breno.lima@nxp.com>
Reviewed-by: Ye Li <ye.li@nxp.com>
(cherry picked from commit d4c01cd3f6f5ba59ca17ebf52f610f629895ac7a)
(cherry picked from commit 4ba6e5aa05ec8872426aa68da3879e8fcd835710)