media: iris: fix error code in iris_load_fw_to_memory()

Return -ENOMEM if memremap() fails.  Don't return success.

Fixes: d19b1633 ("media: iris: implement video firmware load/unload")
Cc: stable@vger.kernel.org
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Dikshita Agarwal <quic_dikshita@quicinc.com>
Signed-off-by: Bryan O'Donoghue <bod@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>