LS2080ARDB: QSPI boot: Secure Boot image validation

Adds header address for PPA to be validated during ESBC phase for
ARCH_LS2088 and QSPI_BOOT. Moves sec_init prior to ppa_init(). It
must be initialized before the PPA.

Signed-off-by: Udit Agarwal <udit.agarwal@nxp.com>
[YS: revised commit message]
Reviewed-by: York Sun <york.sun@nxp.com>