Convert CONFIG_VGA_AS_SINGLE_DEVICE to Kconfig

This converts the following to Kconfig:
   CONFIG_VGA_AS_SINGLE_DEVICE

Once we migrate to driver model for video, we should be able to drop this
option.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/Chuwi_V7_CW0825_defconfig b/configs/Chuwi_V7_CW0825_defconfig
index 8507f73..a67038b 100644
--- a/configs/Chuwi_V7_CW0825_defconfig
+++ b/configs/Chuwi_V7_CW0825_defconfig
@@ -22,3 +22,4 @@
 CONFIG_VIDEO_LCD_SPI_CS="PA0"
 CONFIG_VIDEO_LCD_SPI_SCLK="PA1"
 CONFIG_VIDEO_LCD_SPI_MOSI="PA2"
+CONFIG_CFB_CONSOLE=y