client/site_tests: graphics_VTSwitch uses bmp format

Instead of raw RGB format.  BMP format is more easily viewable.

BUG=chromium-os:36417
TEST=graphics_VTSwitch passes

Change-Id: I748411e1fb5b281d34aa6a7ced2f43b2ba63a15a
Signed-off-by: Simon Que <sque@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/42337
Reviewed-by: Daniel Erat <derat@chromium.org>
Reviewed-by: Ilja H. Friedel <ihf@chromium.org>
Commit-Queue: Ilja H. Friedel <ihf@chromium.org>
Tested-by: Ilja H. Friedel <ihf@chromium.org>
1 file changed