I didn't find any possible modular usage of mca_find_device_by_slot in
the kernel, and this patch therefore removes the EXPORT_SYMBOL.

This patch should be safe since mca-legacy is nothing drivers should
move to.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>