remoteproc: Update last rproc_put users to rproc_free

The transition from rproc_put to rproc_free raced with the review of the
Qualcomm ADSP and ST SLIMproc drivers and these where not updated
accordingly.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
(cherry picked from commit 90a80d88)