tests/kms_cursor_crc: Call drmModeMoveCursor() directly

We're calling drmModeSetCursor() to change the cursor image and never
actually doing a display commit (aside from when we display the cursor),
so call the move ioctl directly rather than igt_plane_set_position() to
ensure the changes actually take effect.

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>