CHROMIUM: avoid using printf %s on long strings

The U-Boot printf() implementation has an output buffer limitation on
output, and so cannot be used for very long output. Instead, puts() has
no such limitation.

BUG=chromium-os:18351
TEST=run on Aebl

Change-Id: I3f3e3b81968f5169a2fe1f581924fa19c3dc1a43
Reviewed-on: http://gerrit.chromium.org/gerrit/4990
Reviewed-by: Che-Liang Chiou <clchiou@chromium.org>
Tested-by: Che-Liang Chiou <clchiou@chromium.org>