drm/vc4: remove check of return value of drm_debugfs functions

drm/vc4: remove check of return value of drm_debugfs functions

Since 987d65d01356 (drm: debugfs: make
drm_debugfs_create_files() never fail), drm_debugfs_create_files() never
fails and should return void. Therefore, remove unnecessary check and
error handling for the return value of drm_debugfs_create_files()
in vc4_debugfs_init().

v2: remove conversion of vc4_debugfs_init() to void to enable individual
compilation and avoid build issues and breakage.

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/20200310133121.27913-5-wambui.karugax@gmail.com