HID: roccat: Introduce module hid-roccat-common

Module hid-roccat-common contains functions used by roccat device driver
modules to reduce code duplication.
At the moment it contains just two wrapper methods for usb_control_msg
that ensure that the buffer used for transfer is dma capable which wasn't
the case before.
The kconfig option is not visible to the user but will be selected by the
device specific drivers.

Signed-off-by: Stefan Achatz <erazor_de@users.sourceforge.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>