drm/v3d: make v3d_debugfs_init() return 0

drm/v3d: make v3d_debugfs_init() return 0

Since commit 987d65d01356 (drm: debugfs: make
drm_debugfs_create_files() never fail), drm_debugfs_create_files() never
fails and should return void. Therefore, remove its use as the
return value of v3d_debugfs_init() and have the function return 0
directly instead.

v2: remove conversion of v3d_debugfs_init() to void to avoid build
breakage and enable individual compilation.

References: https://lists.freedesktop.org/archives/dri-devel/2020-February/257183.html
Signed-off-by: Wambui Karuga <wambui.karugax@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200310133121.27913-4-wambui.karugax@gmail.com