drm/pl111: make pl111_debugfs_init return 0

drm/pl111: make pl111_debugfs_init return 0

Since 987d65d01356 (drm: debugfs: make
drm_debugfs_create_files() never fail) drm_debugfs_create_files()
should return void. Therefore, remove its use as the return value in
pl111_debugfs_init(), and have the function return 0 directly.

v2: have pl111_debugfs_init() return 0 instead of void to avoid build
breakage for 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/20200310133121.27913-13-wambui.karugax@gmail.com