kernel-config: Enable FB_VESA and FRAMEBUFFER_CONSOLE

Commit 159fed47 (nixos/grub: Fix video display on efi) changed BIOS
systems to start in non-text mode as well. Enable FB_VESA to get a
framebuffer console on BIOS systems. Change FRAMEBUFFER_CONSOLE to 'y'
instead of the default 'm' to so the user doesn't need to manually load
the fbcon module anymore.

Other distros have similar defaults, at least on Arch:
    CONFIG_FB_VESA=y
    CONFIG_FRAMEBUFFER_CONSOLE=y
and on Ubuntu (12.04):
    CONFIG_FB_VESA=m
    CONFIG_FRAMEBUFFER_CONSOLE=y

Fixes #8139