Forward port changes from 2.4.19-pre, originally by Keith Owens.
This driver used to build a module target called "aic7xxx_mod.o" and
introduced the MOD_TARGET variable to rename it to "aic7xxx.o" at
modules_install time.
    
Now, we just build "aic7xxx.o" directly, which becomes possible after
renaming aic7xxx.c to aic7xxx_core.c, as done in 2.4.19-pre.