drm/panel: s6d16d0: fix spelling mistake "enble" -> "enable"

Trivial fix to spelling mistake in DRM_DEV_ERROR error message

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20181106154022.9209-1-colin.king@canonical.com