drm/tilcdc: remove check for return value of debugfs functions.

drm/tilcdc: remove check for return value of debugfs functions.

Since 987d65d01356 (drm: debugfs: make
drm_debugfs_create_files() never fail), drm_debugfs_create_files() never
fails. Therefore, remove the check and error handling of the return
value of drm_debugfs_create_files() as it is not needed in
tilcdc_debugfs_init().

Also remove local variables that are not used after the changes.

v2: remove conversion of tilcdc_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>
Acked-by: Jyri Sarha <jsarha@ti.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/20200310133121.27913-3-wambui.karugax@gmail.com