compat-wireless: replace modprobe -l with functional equivilent

compat-wireless: replace modprobe -l with functional equivilent

modprobe -l is either deprecated or removed, so let's replace it
testing [ -z "$(DESTDIR)" ] appeared to only be need due to the fact
that *enable was run directly instead of being run with $(DESTDIR)/

Testing for module presence should now work properly on modern distros
and *enable will be run properly with or without $(DESTDIR) being set.

Signed-off-by: Rick Farina <sidhayn@gmail.com>
Signed-off-by: Luis R. Rodriguez <mcgrof@frijolero.org>