HID: fix hid-roccat-kone for bin_attr API change

After merging the driver-core tree, today's linux-next build (x86_64
allmodconfig) produced these warnings:

drivers/hid/hid-roccat-kone.c:694: warning: initialization from incompatible pointer type
drivers/hid/hid-roccat-kone.c:696: warning: initialization from incompatible pointer type
drivers/hid/hid-roccat-kone.c:701: warning: initialization from incompatible pointer type
drivers/hid/hid-roccat-kone.c:703: warning: initialization from incompatible pointer type
drivers/hid/hid-roccat-kone.c:708: warning: initialization from incompatible pointer type
drivers/hid/hid-roccat-kone.c:710: warning: initialization from incompatible pointer type
drivers/hid/hid-roccat-kone.c:715: warning: initialization from incompatible pointer type
drivers/hid/hid-roccat-kone.c:717: warning: initialization from incompatible pointer type
drivers/hid/hid-roccat-kone.c:722: warning: initialization from incompatible pointer type
drivers/hid/hid-roccat-kone.c:724: warning: initialization from incompatible pointer type
drivers/hid/hid-roccat-kone.c:729: warning: initialization from incompatible pointer type
drivers/hid/hid-roccat-kone.c:731: warning: initialization from incompatible pointer type

Introduced by commit 867040163f10f2b52b45bc573f330d6eb28f5914 ("sysfs:
add struct file* to bin_attr callbacks") from the driver-core tree
interacting with commit 14bf62cd ("HID:
add driver for Roccat Kone gaming mouse") from the hid tree.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>