sys-kernel/coreos-modules: Reenable console support for DRM

When the virtio graphic mode instead of qemu's bochs was used, the
interactive console did not show up because fbdev emulation recently
got disabled.
Reenable fbdev emulation and also add the "simple" FB DRM driver for
UEFI to make TTM_HELPER and VRAM_HELPER available for the nvidia driver
(which is needed when fbdev emulation is enabled).

Fixes flatcar/Flatcar#1834

Signed-off-by: Kai Lueke <[email protected]>

Author: pothos

changelog/bugfixes/2025-08-11-drm-console.md

@@ -0,0 +1 @@
+- Reenabled console support for DRM drivers, so that with the virtio graphics driver the interactive console is shown again after boot ([Flatcar#1834](https://github.com/flatcar/Flatcar/issues/1834))

sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-modules/files/commonconfig-6.12

@@ -169,9 +169,12 @@ CONFIG_DM_VERITY=m
 CONFIG_DM_ZERO=m
 CONFIG_DNS_RESOLVER=y
 CONFIG_DRM=m
+CONFIG_DRM_FBDEV_EMULATION=y
+CONFIG_DRM_SIMPLEDRM=m
+CONFIG_DRM_TTM_HELPER=m
 CONFIG_DRM_VIRTIO_GPU=m
+CONFIG_DRM_VRAM_HELPER=m
 CONFIG_DST_CACHE=y
-# CONFIG_DRM_FBDEV_EMULATION is not set
 CONFIG_DUMMY=m
 CONFIG_DYNAMIC_DEBUG=y
 CONFIG_E100=m