remoteproc: Modify the function names

The functions rproc_add_virtio_devices() and rproc_fw_config_virtio()
are reduced to trigger auto-boot only. Modify these function names and
related comments to reflect their current state.

This patch does not add any functional change.

Signed-off-by: Sarangdhar Joshi <spjoshi@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>