abuild: Don't print "Using payload ..." message in quiet mode

It's not useful in quiet mode, and is very distracting.

Change-Id: I59dc8caa22b66980560d5afb76eae801efaa29ad
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/124
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>