bcm2835: Add simiple-framebuffer for use with fkms

When the fkms dtb overlay is used only the simple-framebuffer is
presented as a usable video display. So, add "simple-framebuffer"
compatible to enable video driver bcm2835.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Meng Li <Meng.Li@windriver.com>
diff --git a/drivers/video/bcm2835.c b/drivers/video/bcm2835.c
index c296293..1494252 100644
--- a/drivers/video/bcm2835.c
+++ b/drivers/video/bcm2835.c
@@ -54,6 +54,9 @@
 	{ .compatible = "brcm,bcm2835-hdmi" },
 	{ .compatible = "brcm,bcm2711-hdmi0" },
 	{ .compatible = "brcm,bcm2708-fb" },
+#if !IS_ENABLED(CONFIG_VIDEO_DT_SIMPLEFB)
+	{ .compatible = "simple-framebuffer" },
+#endif
 	{ }
 };