Fix the uninitialized symbol 'rv' in the function ish_fw_xfer_direct_dma
to resolve the following warning from the smatch tool:
drivers/hid/intel-ish-hid/ishtp-fw-loader.c:714 ish_fw_xfer_direct_dma()
error: uninitialized symbol 'rv'.
Initialize 'rv' to 0 to prevent undefined behavior from uninitialized
access.

Cc: stable@vger.kernel.org
Fixes: 91b22810 ("HID: intel-ish-hid: ISH firmware loader client driver")
Signed-off-by: SurajSonawane2415 <surajsonawane0215@gmail.com>
Link: https://patch.msgid.link/20241004075944.44932-1-surajsonawane0215@gmail.comSigned-off-by: Benjamin Tissoires <bentiss@kernel.org>