MAINTAINERS: Add entry for Solomon SSD130x OLED displays DRM driver

To make sure that tools like the get_maintainer.pl script will suggest
to Cc me if patches are posted for this driver.

Also include the Device Tree binding for the old ssd1307fb fbdev driver
since the new DRM driver was made compatible with the existing binding.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220214133915.3278886-1-javierm@redhat.com