Libpayload needs to clear the bss region.

Libpayload needs to clear the bss region.

Libpayload shouldn't count on coreboot or other payloads to clear memory. This fixes problems with payloads being loaded after or on top of each other.

Change-Id: I30303d47e465e8921f47acab667c7998ba79fca7
Signed-off-by: Marc Jones <marcj303@gmail.com>
Reviewed-on: http://review.coreboot.org/66
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>