drm/sun4i: Fix an error handling path in 'sun4i_drv_bind()'

Commit 070badfa ("drm/sun4i: call drm_vblank_init with correct number
of crtcs") has moved some code without updating the error handling gotos
accordingly.

Branch to the correct label and remove a now unused lablel.

Fixes: 070badfa

 ("drm/sun4i: call drm_vblank_init with correct number of crtcs")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180311231909.5381-1-christophe.jaillet@wanadoo.fr