make_netboot: Enable VT and FB console on netboot kernel.

Currently Frecon cannot fit into initramfs (which is used by netboot images,
same as recovery and factory installer images) so we want to enforce vtconsole
and fbconsole until Frecon is ready.

BUG=chromium:440878
TEST=./make_netboot.sh # See console in the new netboot kernel.

Change-Id: I56b6818b112f01e7a5e12de80114bc1951c1e5af
Reviewed-on: https://chromium-review.googlesource.com/248010
Reviewed-by: Bowgo Tsai <bowgotsai@chromium.org>
Commit-Queue: Hung-Te Lin <hungte@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>
diff --git a/make_netboot.sh b/make_netboot.sh
index 6161cd4..03ea092 100755
--- a/make_netboot.sh
+++ b/make_netboot.sh
@@ -64,7 +64,7 @@
 
 # Build initramfs network boot image
 echo "Building kernel"
-export USE='vfat netboot_ramfs i2cdev tpm'
+export USE="fbconsole vtconsole netboot_ramfs tpm i2cdev vfat"
 export EMERGE_BOARD_CMD="emerge-${FLAGS_board}"
 emerge_custom_kernel ${temp_build_path}