Use BMP format for all master images.

Since both UEFI BIOS and U-Boot display BMP images (although with different
compression schemes), we might as well just use that format for the master
images.

We may still need to crop, scale, or compress these master images to the
platform-specific formats, of course. This change also adds an example
Makefile to produce the scaled images for x86 platforms.

BUG=chromium-os:18631
TEST=none

Change-Id: Idd18d66ea46502065c6f3707f625908a892a0cbd
Reviewed-on: http://gerrit.chromium.org/gerrit/5619
Tested-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
446 files changed