lame: Remove --enable-debug workaround.

This is not needed since BR2_ENABLE_DEBUG does not set this flag
anymore.

Signed-off-by: Johan Oudinet <johan.oudinet@gmail.com>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>