dtoverlays: Switch ssd1306 to use the DRM driver

Both drivers/gpu/drm/solomon/ssd130x-i2c.c and
drivers/video/fbdev/ssd1307fb.c were registering the compatible
"solomon,ssd1306fb-i2c", so bringing ambiguity as to which one
got loaded.

fbdev is largely deprecated, so adopt the updated compatible
for the drm driver.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>

Author: 6by9

arch/arm/boot/dts/overlays/ssd1306-overlay.dts

@@ -14,7 +14,7 @@
 	    #size-cells = <0>;
 
 	    ssd1306: oled@3c{
-		compatible = "solomon,ssd1306fb-i2c";
+		compatible = "solomon,ssd1306";
 		reg = <0x3c>;
 		solomon,width = <128>;
 		solomon,height = <64>;