remoteproc: qcom: wcnss: remove unused qcom_iris_driver declaration

qcom_iris_driver has been removed since
commit 1fcef985 ("remoteproc: qcom: wcnss: Fix race
with iris probe"), so remove it.

Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220911090637.3208939-1-cuigaosheng1@huawei.com