fbdev: sh_mobile_hdmi: simplify the EDID reading procedure

The present SH-Mobile HDMI driver reads and parses the EDID block into a
variable screeninfo object, but since it is still unable to dynamically
reconfigure the framebuffer, it overwrites the EDID information with preset
values again. This patch just uses a temporary variable to store the EDID
timing information instead.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>