video: ssd1307fb: Add devicetree configuration of display setup

Various displays have differences that only mean initializing the display
driver IC with different fixed register values. Defining these in
devicetree offers easier way to adapt the driver to new displays than
requiring a patch to the kernel.

This adds devicetree properties needed to make the initialization match
the example setup as offered by Densitron for their 128x36 display.

It also makes some old one bit parameter handling a little cleaner.

Signed-off-by: Marko Kohtala <marko.kohtala@okoko.fi>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: Michal Vokáč <michal.vokac@ysoft.com>
[b.zolnierkie: fix parenthesis alignment]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190618074111.9309-7-marko.kohtala@okoko.fi