video: restore CONFIG_VIDCONSOLE_AS_LCD as boolean

This patch restores CONFIG_VIDCONSOLE_AS_LCD as boolean
and introduce a separate sting as CONFIG_VIDCONSOLE_AS_NAME
to search this string in stdout used as videoconsole.

This patch avoid issue with board defconfig or code expecting
CONFIG_VIDCONSOLE_AS_LCD as boolean.

Fixes: 22b897a1 ("video: extend stdout video console work-around for 'vga'")
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>