drm: flip cirrus driver status to "obsolete".

Also update Kconfig help text, explaining things:

Cirrus is obsolete, the hardware was designed in the 90ies
and can't keep up with todays needs.  More background:
https://www.kraxel.org/blog/2014/10/qemu-using-cirrus-considered-harmful/

Better alternatives are:
  - stdvga (DRM_BOCHS, qemu -vga std, default in qemu 2.2+)
  - qxl (DRM_QXL, qemu -vga qxl, works best with spice)
  - virtio (VIRTIO_GPU), qemu -vga virtio)
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

MAINTAINERS

@@ -4116,7 +4116,8 @@ M:	Dave Airlie <airlied@redhat.com>
 M:	Gerd Hoffmann <kraxel@redhat.com>
 L:	virtualization@lists.linux-foundation.org
 T:	git git://git.kraxel.org/linux drm-qemu
-S:	Odd Fixes
+S:	Obsolete
+W:	https://www.kraxel.org/blog/2014/10/qemu-using-cirrus-considered-harmful/
 F:	drivers/gpu/drm/cirrus/
 
 RADEON and AMDGPU DRM DRIVERS

drivers/gpu/drm/cirrus/Kconfig

@@ -7,3 +7,12 @@ config DRM_CIRRUS_QEMU
 	 This is a KMS driver for emulated cirrus device in qemu.
 	 It is *NOT* intended for real cirrus devices. This requires
 	 the modesetting userspace X.org driver.
+
+	 Cirrus is obsolete, the hardware was designed in the 90ies
+	 and can't keep up with todays needs.  More background:
+	 https://www.kraxel.org/blog/2014/10/qemu-using-cirrus-considered-harmful/
+
+	 Better alternatives are:
+	   - stdvga (DRM_BOCHS, qemu -vga std, default in qemu 2.2+)
+	   - qxl (DRM_QXL, qemu -vga qxl, works best with spice)
+	   - virtio (DRM_VIRTIO_GPU), qemu -vga virtio)