ARC: [plat-hsdk] Switch DisplayLink driver from fbdev to DRM

Currently there're 2 different implementations of the driver for
DisplayLink USB2.0-to-HDMI/DVI adapters: older FBDEV and modern true
DRM.

We initially decided to use FBDEV version just because with it
/dev/fbX is usable from user-space while in DRM version
with DRM_FBDEV_EMULATION user-space cannot draw anything on a real
screen, for more info read [1].

But today /dev/fbX is not that important as more and more software
projects switch to use of DRI (/dev/dri/cardX).

But what's even more important DRM driver allows building of complicated
graphics processing chains. The most important for us is rendering of
3D on a dedicated GPU while outputting video through a simpler
bitstreamer like DisplayLink. So let's use much more future-proof
driver from now on.

[1] https://lists.freedesktop.org/archives/dri-devel/2017-December/159519.html

Signed-off-by: Alexey Brodkin <[email protected]>
Signed-off-by: Vineet Gupta <[email protected]>

arch/arc/configs/hsdk_defconfig

@@ -49,10 +49,11 @@ CONFIG_SERIAL_8250_DW=y
 CONFIG_SERIAL_OF_PLATFORM=y
 # CONFIG_HW_RANDOM is not set
 # CONFIG_HWMON is not set
+CONFIG_DRM=y
+# CONFIG_DRM_FBDEV_EMULATION is not set
+CONFIG_DRM_UDL=y
 CONFIG_FB=y
-CONFIG_FB_UDL=y
 CONFIG_FRAMEBUFFER_CONSOLE=y
-CONFIG_USB=y
 CONFIG_USB_EHCI_HCD=y
 CONFIG_USB_EHCI_HCD_PLATFORM=y
 CONFIG_USB_OHCI_HCD=y