lxfb: add power management functionality

This adds the ability to suspend/resume the lxfb driver, which includes:
  - Register and palette saving code; registers are stored in lxfb_par.
    A few MSR values are saved as well.
  - lx_powerup and lx_powerdown functions which restore/save registers and
    enable/disable graphic engines.
  - lxfb_suspend/lxfb_resume

Originally based on a patch by Jordan Crouse.

[akpm@linux-foundation.org: be conventional, save an ifdef]
Signed-off-by: Andres Salomon <dilinger@debian.org>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: Jordan Crouse <jordan.crouse@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>