Fix to allow compiling outside of the source tree, ie. the correct way
/sound/isa/opti9xx
-rw-r--r-- Makefile
-rw-r--r-- miro.c
-rw-r--r-- opti92x-ad1848.c
-rw-r--r-- opti92x-cs4231.c
-rw-r--r-- opti93x.c