drm/etnaviv: remove check for return value of drm_debugfs_create_files()

drm/etnaviv: remove check for return value of drm_debugfs_create_files()

Since commit 987d65d01356 (drm: debugfs: make
drm_debugfs_create_files() never fail), drm_debugfs_create_files() never
fails and only returns 0. Therefore, remove the unnecessary check of its
return value and error handling in etnaviv_debugfs_init() and have the
function return 0 directly.

v2: have etnaviv_debugfs_init() return 0 instead of void to ensure
individual compilation and avoid build breakage.

References: https://lists.freedesktop.org/archives/dri-devel/2020-February/257183.html
Signed-off-by: Wambui Karuga <wambui.karugax@gmail.com>
Acked-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200310133121.27913-8-wambui.karugax@gmail.com