Create a new file for common vboot UI functions

Rather than having vboot_ui be the common file between that and
vboot_ui_menu, create a new file.

For now just move over vb2_error_beep(). The other common functions are
being removed in future CLs.

BUG=chromium:837018
BRANCH=none
TEST=FEATURES=test emerge-grunt --nodeps vboot_reference

Change-Id: Iff6917642ff79ea0b5cce60b383876b6f7174d20
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1310794
Reviewed-by: Julius Werner <jwerner@chromium.org>
6 files changed