There was a driver (btusb.c) change to include the device's
HW_VARIANT in the filename to support multiple devices and
this patch fixes the firmware filename for WsP to align with
that patch.

WsP(WindStorm Peak) is also known as Intel Bluetooth 8264.
Signed-off-by: Tedd Ho-Jeong An <tedd.an@intel.com>
Signed-off-by: Kyle McMartin <kyle@kernel.org>