sm501fb: control panel pin usage with platform data flags

This patch makes it possible to control panel pins usage with flags passed
from the platform data.  Without this patch the sm501fb driver always controls
the VBIASEN and FPEN pins.  The polarity and use of these pins are very
platform specific, so this patch introduces the flags
SM501FB_FLAG_PANEL_USE_VBIASEN and SM501FB_FLAG_PANEL_USE_FPEN which enable
the use of these pins.

This patch is needed to support the a Sharp LQ104V1DG21 lcd panel on SuperH
platforms such as R2D-1 and R2D-PLUS boards.  Letting the sm501fb driver
control the FPEN and VBIASEN pins like today just results in lcd panel
flicker.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>