Rename drivers/hid/hid-drff.c (a DragonRise Inc. force feedback gamepad driver)
to driver/hid/hid-dr.c.

This prepares it for addition of support for another gamepad, without force
feedback.
Signed-off-by: NNikolai Kondrashov <spbnick@gmail.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>