Improve SPI status register pretty printing

This backports the upstream `commit 6ee37e28`.

BUG=chromium:478356
BRANCH=none
TEST=still builds

Change-Id: Ibd83f658b35621407cc0d16909066c7ffde6c4a5
Signed-off-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1502474
Reviewed-by: David Wells <dawells@google.com>
6 files changed