Fixes gcc '-Wunused-but-set-variable' warning:

drivers/gpu/drm/drm_fb_helper.c: In function 'drm_pick_crtcs':
drivers/gpu/drm/drm_fb_helper.c:2373:43: warning:
 variable 'connector_funcs' set but not used [-Wunused-but-set-variable]
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1536722130-108819-1-git-send-email-yuehaibing@huawei.com