module references

[Hollis Blanchard]

Right now I'm getting a lot of these:
        ../fs/affs.c: In function `grub_mod_init':
        ../fs/affs.c:556: warning: unused parameter `mod'
... in fact, one for every GRUB_MOD_INIT in fs/ and partmap/, it seems.

This led me to examine the module reference counting system. Most 
filesystems don't do anything more than set a "my_mod" global variable, 
and never use it. fat.c, on the other hand, seems to actually be trying 
to use a refcount.

Are modules ever automatically unloaded? When? If so, we need a lot 
more reference counting. If not, we've got some unnecessary complexity 
we should remove.

-Hollis