HID: rename hid-drff.c to hid-dr.c

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: Nikolai Kondrashov <spbnick@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/Makefile

@@ -34,7 +34,7 @@ obj-$(CONFIG_HID_CANDO)		+= hid-cando.o
 obj-$(CONFIG_HID_CHERRY)	+= hid-cherry.o
 obj-$(CONFIG_HID_CHICONY)	+= hid-chicony.o
 obj-$(CONFIG_HID_CYPRESS)	+= hid-cypress.o
-obj-$(CONFIG_HID_DRAGONRISE)	+= hid-drff.o
+obj-$(CONFIG_HID_DRAGONRISE)	+= hid-dr.o
 obj-$(CONFIG_HID_EMS_FF)	+= hid-emsff.o
 obj-$(CONFIG_HID_EGALAX)	+= hid-egalax.o
 obj-$(CONFIG_HID_ELECOM)	+= hid-elecom.o