kodi: s/BR2_DL_DIR/DL_DIR/

BR2_DL_DIR is not to be used by the package's Makefile.

Signed-off-by: Maxime Hadjinlian <maxime.hadjinlian@gmail.com>
Acked-by: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>