[C-Api] Modify API names and its comments

[C-Api] Modify API names and its comments

This patch modify API names and its comments to comply with API Guide.
Detailed items are as below.

* Modify the comments to comply with API Guide
* ml_single_inference() -> ml_single_invoke()
* ml_pipeline_src_put_handle () -> ml_pipeline_src_release_handle ()
* ml_pipeline_switch_put_handle () -> ml_pipeline_switch_release_handle ()
* ml_pipeline_valve_put_handle () -> ml_pipeline_valve_release_handle ()

Signed-off-by: Sangjung Woo <sangjung.woo@samsung.com>