video: cfb_console: Make the software cursor non-destructive

When printing the string "\r\n" to the framebuffer console, the first
character of the current line was being replaced with a space. The "boot"
prompt would become the "oot" prompt. This change makes the cursor
non-destructive so that no matter where it goes on its way to where it's
supposed to be, the end result is that the cursor is where it's supposed to
be with the other text preserved.

Signed-off-by: Gabe Black <gabeblack@chromium.org>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Anatolij Gustschin <agust@denx.de>