drm/nouveau: Remove file nouveau_fbcon.c

Commit 4a16dd9 ("drm/nouveau/kms: switch to drm fbdev helpers")
converted nouveau to generic fbdev emulation. The driver's internal
implementation later got accidentally restored during a merge commit.
Remove the file from the driver. No functional changes.

v2:
	* point Fixes tag to merge commit (Alex)

Signed-off-by: Thomas Zimmermann <[email protected]>
Reviewed-by: Alex Deucher <[email protected]>
Fixes: 4e291f2 ("Merge tag 'drm-misc-next-2022-11-10-1' of git://anongit.freedesktop.org/drm/drm-misc into drm-next")
Cc: Ben Skeggs <[email protected]>
Cc: Karol Herbst <[email protected]>
Cc: Lyude Paul <[email protected]>
Cc: Thomas Zimmermann <[email protected]>
Cc: Javier Martinez Canillas <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Dave Airlie <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: Thomas Zimmermann