ps3fb: reorganize modedb handling

Reorganize modedb handling:
  - Reorder the video modes in ps3fb_modedb, for easier indexing using
    PS3AV_MODE_* numbers,
  - Introduce ps3fb_native_vmode(), to convert from native (PS3AV_MODE_*) mode
    numbers to struct fb_videomode *,
  - Rename and move ps3fb_default_mode() to ps3fb_vmode().

Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>