mainboards: fix spd generation

echo is evaluated by a shell builtin producing non-binary
spd data of the form '-e -n \<byte>'. Correct this by
using printf builtin which does the equivalent and is
more cross platform friendly.

Boards changed:
gizmosphere/gizmo
gizmosphere/gizmo2
google/bolt
google/falco
google/link
google/peppy
google/rambi
google/samus
google/slippy
pcengines/apu1

Change-Id: Iefdaf59903b9682cc88c94fd991883b560616492
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/9196
Tested-by: build bot (Jenkins)
Reviewed-by: Marc Jones <marc.jones@se-eng.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
10 files changed