EDAC, altera: Remove useless casts

The altera EDAC driver refers to its per-device data
using a cast to '(void *)', which makes the pointer
non-const, though both the source and destination are
actually const.

Removing the annotation makes the reference (almost)
fit into a single line for improved readability, and
ensures that it is actually defined as const.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thor Thayer <tthayer@opensource.altera.com>
Cc: Alan Tull <atull@opensource.altera.com>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/1460837650-1237650-1-git-send-email-arnd@arndb.de
Signed-off-by: Borislav Petkov <bp@suse.de>