drm/arcpgu: Really delete file

Somehow this got forgotten when I applied the patch in

commit e2c406ea
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Tue Jan 12 09:43:54 2021 +0100

    drm/arc: Inline arcpgu_crtc.c

Fixes: e2c406ea ("drm/arc: Inline arcpgu_crtc.c")
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20210226133647.1403642-1-daniel.vetter@ffwll.ch