arch/Kconfig.nxp: Re-organize slightly

Make all of the CHAIN_OF_TRUST options be under a single menu and add a
comment for the rest, so the resulting config file reads more clearly.
Remove duplicate CHAIN_OF_TRUST options from
board/congatec/common/Kconfig.  Remove duplicate NXP_ESBC config
questions and move to arch/Kconfig.nxp.

Signed-off-by: Tom Rini <trini@konsulko.com>