remoteproc: qcom: q6v5: Avoid handling handover twice

remoteproc: qcom: q6v5: Avoid handling handover twice

A remoteproc could theoretically signal handover twice. This is unexpected
and would break the reference counting for the handover resources (power
domains, clocks, regulators, etc), so add a check to prevent that from
happening.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Stephan Gerhold <stephan.gerhold@linaro.org>
Link: https://lore.kernel.org/r/20250820-rproc-qcom-q6v5-fixes-v2-2-910b1a3aff71@linaro.org
Signed-off-by: Bjorn Andersson <andersson@kernel.org>