memtest86+: Fix redrawing the display for serial console

When building memtest86+ with serial console, refreshing the screen
clears the screen buffer which caused most of the display blank.
For serial console whole screen should be redrawn and screen
buffer must not be cleared when refreshing.

Change-Id: I832de1743970f5b320b58ba43b0ff9cb4da1cb7f
Signed-off-by: Michał Żygowski <michal.zygowski@3mdeb.com>
Reviewed-on: https://review.coreboot.org/23089
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martinroth@google.com>
1 file changed