remoteproc: rename subdev probe and remove functions

Rename functions used when subdevices are started and stopped to
reflect the new naming scheme.

Tested-by: Fabien Dessenne <fabien.dessenne@st.com>
Signed-off-by Alex Elder <elder@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>