console: probe PCI VGA device using driver_manager

Load VGAConsole only when PCI VGA adapter available on a Hypervisor.

Signed-off-by: Takuya ASADA <syuu@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
console: use existing isa_serial_console instance instead of creating new one

Acked-by: Claudio Fontana <claudio.fontana@huawei.com>
Signed-off-by: Takuya ASADA <syuu@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
upload_manifest.py: Fix infinite loop in unsymlink

If symlink points to a path that does not exist, return "f" instead of
entering an infinite loop.

Cc: Nadav Har'El <nyh@cloudius-systems.com>
Reviewed-by: Tomasz Grabiec <tgrabiec@gmail.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>