The page_offset was only applied to the end of the page range. This caused
the display updates to cause a scrolling effect on the display because the
amount of data written to the display did not match the range display
expected.

Fixes: 301bc067 ("video: ssd1307fb: Make use of horizontal addressing mode")
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>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190618074111.9309-4-marko.kohtala@okoko.fi