Move the payloads section of the kconfig tree out of the top level
kconfig file and into a separate Kconfig just for payloads before
it starts to get added to.
Change-Id: I4f52818f862bf1aeba538c1c6ed93211a78b9853
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/13608
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>