Allow the saving and restoration of VGA text mode.  The state is saved on the
first open and restored on the last close.  Because of the non-linear mapping
of the VGA registers to the MMIO space, this will be done only on X86
platforms where the device is the primary display.

An echo 0 > /sys/class/vtconsole/vtcon1/bind will convert the display from
graphics to text mode.
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>