configs/pc_x86_64_{bios, efi}_defconfig: new samples

configs/pc_x86_64_{bios, efi}_defconfig: new samples

Add two new sample defconfigs oriented towards real PC targets.

It adds two variants for BIOS and EFI boot strategy.

On the build side we enable eudev to autoload relevant kernel
modules/support when necessary.

It adds a bunch of drivers and extra filesystem support which is by no
means extensive/complete, mostly geared towards the hardware i've got at
hand to test with.
This is accomplished by adding on top of the Qemu x86_64 kernel sample
config.

Build connman since by using eudev network interfaces get renamed on
boot thus complicating any form of automatic and friendly bringup.
It also makes Wi-Fi configuration/support easier.

In principle these base defconfigs should work just fine for other
storage media != pendrive like sata or ssd disk, however driver support
isn't there quite yet, and pendrive is mostly supported by usb storage
plus the usual usb host controller drivers.

Tested on old Lenovo laptop (BIOS) and Asus Zenbook (EFI).

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>