multiboot-x86: pass framebuffer information when requested

When the kernel requests video information, pass it the
framebuffer information in the multiboot header from
the linux framebuffer ioctl's.

With the arch specific --reset-vga or --consolve-vga
options, purgatory will reset the framebuffer so pass
information for standard ega text mode.

Signed-off-by: Friedemann Gerold <cinap_lenrek@felloff.net>
Signed-off-by: Simon Horman <horms@verge.net.au>