drm/sti:fix spelling mistake: "compoment" -> "component"

Trivial fix to spelling mistake in DRM_ERROR message

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170513224150.19955-1-colin.king@canonical.com